Residential streets around Rome's cathedral, the green calm of the Celio and Aventino hills, and the earthy, food-obsessed district of Testaccio below them.
Last updated August 23, 2026
In a nutshell: this sprawling, multifaceted quadrant of south-east Rome mixes heavyweight sightseeing with everyday urban texture: quiet residential lanes, peaceful hilltop gardens, working-class streets and one of the city's liveliest food markets. The headline acts are Rome's cathedral, the Basilica di San Giovanni in Laterano, the layered underground of San Clemente, the colossal Terme di Caracalla, the Nuovo Mercato di Testaccio and a keyhole framing one of the city's most magical views. The Colosseum and ancient Rome sit a short walk from the Celio, the historic centre lies just beyond them, and Trastevere glitters across the river from the Aventino.
| Sight | Ticket | Notes |
|---|---|---|
| Basilica di San Giovanni in Laterano | Free | Security check; cloister €6 with audio guide, €4 without |
| Santuario della Scala Santa | Free; Sancta Sanctorum €3.50 | Sacred staircase climbed on the knees |
| Basilica di San Clemente | Church free; underground €10/€5 | Book the underground levels online |
| Basilica dei SS Quattro Coronati | Free; Aula Gotica tours €10 | Bimonthly tours of the Gothic hall |
| Chiesa di Santo Stefano Rotondo | Free | Graphic 16th-century martyrdom frescoes |
| Case Romane del Celio | €8 adult, €6 reduced | Frescoed Roman houses under the Celio |
| Cave del Tempio di Claudio | €12 plus €5 ticket | Underground quarry tour with Roma Sotterranea |
| Museo della Forma Urbis | €9 adult, €6.50 reduced | Walk over the ancient marble map |
| Terme di Caracalla | Around €12 with exhibitions | Free on the month's first Sunday |
| Nuovo Mercato di Testaccio | Free | Legendary food stalls at lunchtime |
| Monte Testaccio | Tour €4 adult, €3 reduced | Artificial hill of amphora shards |
| Cimitero Acattolico | Free | Keats, Shelley and Gramsci rest here |
| Villa del Priorato di Malta | Free | The celebrated keyhole view |
| Basilica di Santa Sabina | Free | Original 5th-century doors |
| Roseto Comunale | Free | 1100+ rose varieties in spring |
| Mattatoio | Free | Contemporary art in the old slaughterhouse |
Each sub-neighbourhood is walkable on its own, whether you are covering San Giovanni & Celio or Aventino & Testaccio, but hopping between them calls for public transport.
Step beyond the famous basilica and San Giovanni reveals itself as a workaday district of shops, bars, apartment towers and increasingly fashionable eateries. The Celio, meanwhile, stays hushed and church-filled, a pocket of contemplative calm.
Next door to the Lateran, this sanctuary radiates a devotion that has faded from the city's more sterile, museum-like churches. Its prize is the flight of marble steps known as the Scala Santa, reputed to be the very flight Jesus climbed in the Jerusalem palace of Pontius Pilate. Believers treat the treads as holy, going up on their knees and murmuring a prayer at every one of the 28 steps. At the summit, shut behind an iron grille, glows the Sancta Sanctorum, a chapel so revered it earned the nickname 'Holy of Holies' and for centuries served as the popes' private quarters. Entry to the staircase is free; the Sancta Sanctorum costs €3.50.
Tip: Even if you are not religious, walk quietly and give the pilgrims space: watching them ascend on their knees is part of the experience.
Few sightseers make the detour to this fortified church, yet its medieval paintings are well worth the stop. Inside the Oratorio di San Silvestro, open 9.30am to noon Monday to Saturday, a 13th-century cycle tells how Emperor Constantine met Sylvester I and how the Donation of Constantine, as the document is known, came to be. The basilica has stood here since the 6th century, rebuilt into its present shape in the 1100s after Norman raiders wrecked the earlier building in 1084. To see the painted Aula Gotica, up on the Torre Maggiore's first floor and one of the few Gothic halls left in Rome, you must join one of the twice-monthly tours, which cost €10 per person; dates are on aulagoticasantiquattrocoronati.it.
The Donation of Constantine usually tops the list of medieval forgeries. In it, the emperor supposedly bequeathed to Pope Sylvester I (reigned 314-35) and his heirs both Rome and the whole Western Roman Empire, along with supremacy over the church seats at Antioch, at Alexandria, at Constantinople and at Jerusalem, and over every church on Earth. For hundreds of years the document was treated as authentic and quoted by popes defending their territorial ambitions, until the philosopher Lorenzo Valla exposed it as a fake in 1440. Its true date remains unknown, though the consensus puts it in the second half of the 700s.
Few of Rome's art-packed churches are as unsettling as this one. A 16th-century fresco cycle, commissioned while the Counter-Reformation was raging and the Catholic Church hoped to check Protestantism and fire up a fresh generation of believers, lines the walls with the ordeals inflicted on early Christian martyrs. Charles Dickens, who saw the paintings in 1846, declared that no dream could match such a waking spectacle of horror and slaughter. The church itself, set within its own walled and leafy grounds and built in the late 400s, is among Rome's oldest, and beneath the gore it is a lovely space: a circular, light-filled hall where columns of marble ring the high altar.
Tip: The frescoes are explicit and can unsettle children, and plenty of adults, so decide in advance whether the shudder is worth it.
Rome's cathedral and the pope's own church in his role as Bishop of Rome, the Basilica di San Giovanni in Laterano is also one of the city's most unmissable landmarks. Consecrated in 324 CE, it was Rome's first Christian basilica, and it remains the mater et caput, a Latin title meaning 'mother and head', of every Catholic church.
The church is the senior of Rome's four papal basilicas, built on Constantine's orders and consecrated by Sylvester I in 324 CE. It served as the chief pontifical church until 1309, when the papacy decamped to Avignon, and the neighbouring Palazzo Lateranense acted as the popes' residence throughout that era. Both buildings slid into ruin while the papacy was away in France, and when Gregory XI finally came back in 1377 he opted for the fortified Vatican instead. Of the original structure almost nothing survives: the building was remade again and again, and the version you see today is chiefly the work of Francesco Borromini's baroque overhaul in the mid-1600s.
Galilei's immense white facade of 1735 is best judged from across the piazza. Along its summit stand fifteen figures, each 7m tall: Christ between St John the Baptist and John the Evangelist, with the Twelve Apostles ranged alongside. Behind the enormous columns of the portico, seek out the bronze door leaves brought over from the Forum's Curia building, and the Holy Door at the far right, unsealed only during Jubilee years.
The Lateran has stood at the centre of Catholic Jubilees, or Holy Years, since 1425, when its Holy Door was first thrown open for the occasion, a tradition that continues today. Pilgrims who come in a Holy Year can still earn a plenary indulgence. Rome is currently giving the basilica's piazza a €15 million refurbishment to welcome the 2025 Jubilee.
Step inside and the sheer scale hits you first: this is an interior that makes you feel small. The marble-sheathed nave owes its current look to Borromini, who refashioned it for the 1650 Jubilee yet spared earlier treasures, among them the gilded, coffered ceiling from the 1500s and the Cosmati pavement laid in the 1400s. Along the wide central nave, statues of the apostles from the 1700s, every one 4.6m tall, occupy their own dramatic niches. A 14th-century Gothic baldachin soars above the papal altar, reputed to guard the skulls of Sts Peter and Paul; the confessio before it holds Martin V's tomb, set at the altar's foot beside a wooden effigy of St John the Baptist. Mosaics sparkle across the great apse, a handful of them survivors from the 4th-century original, though the majority date from the 1800s. Back near the entrance, an unfinished fresco by Giotto covers the first pillar of the right-hand aisle, and the next column carries the memorial of Sylvester II (reigned 999-1003), which locals claim groans whenever a pope is about to die.
The cloister lies through a doorway left of the high altar; built in the 1200s, it is among the most tranquil corners in Rome (€6 with an audio guide, €4 without). Its arcades frame a central garden, lined with columns that twist elegantly, plus marble fragments salvaged from the original church: among them the remnants of a papal throne from the 400s and the inscribed texts of a pair of papal bulls.
For a crash course in Rome's layered past, no site beats San Clemente. The basilica you enter at street level is a 12th-century building, yet under it sits a 4th-century church, and beneath that, in turn, lie Roman-era structures and a pagan shrine from the 100s.
The upper church, entered across a colonnaded atrium, guards genuine treasures: the apse holds a radiant 12th-century mosaic of the Trionfo della Croce, the Triumph of the Cross, while frescoes from the 1400s, painted by Masolino, depict a crucifixion and scenes from St Catherine's story.
The church itself costs nothing, but the buried levels need a ticket (€10 adult, €5 reduced) bought online in advance; allow roughly thirty minutes below ground, where a printed leaflet explains what you are seeing. Steps from the sacristy drop into the 4th-century basilica inferiore, wrecked during the Norman sack of 1084 yet still decorated with faded frescoes telling St Clement's story. One of them, just left of the high altar, may hold the earliest recorded swear word in vulgar Italian. A further staircase leads into dark corridors lined with rooms of a 1st-century Roman house and a structure thought to be the imperial mint of the 1st century. The highlight, however, is the mithraeum of the 100s, a temple of the god Mithras whose altar shows the god despatching a bull. Deep below everything, an underground spring rushes beneath a grille in the floor.
The buried temple honours Mithras, a cult that swept ancient Rome, especially among legionaries. Legend told how the Sun commanded the youthful god to slaughter a bull; the creature's death brought forth life, with crops and vegetation springing from its blood. Shrines to Mithras, the mithraeums, were virtually always set in caves or underground, since caverns stood for the cosmos itself. There, initiates passed through elaborate ceremonies and shared bread and water meant to stand in for the bull's flesh and blood.
Just a short climb from the Colosseum, the gardens of the Villa Celimontana offer blessed relief from the crowds. The grounds spread out from a 16th-century villa that now lodges the Italian Geographical Society, and they stay serene for most of the year before a celebrated summer programme of swing and jazz concerts takes over.
Tip: Come in summer for the concerts, or on any other day for quiet paths, shade and grass that is usually almost all yours.
The Celio hides a fascinating underground world, and these Case Romane are its showpiece: roughly twenty rooms, many still painted with their original frescoes. Until the 200s CE the chambers served as shops and storerooms; around then they were converted into a domus, a townhouse. Tradition links the house to two soldiers of Rome, John and Paul, who are not the apostles of the same names and who were supposedly beheaded on the orders of the emperor Julian. Hard proof is lacking, though excavations show that later the chambers hosted Christian worship. The site is tucked under the Basilica dei SS Giovanni e Paolo al Celio, with its entrance on the Clivo di Scauro, that picturesque Roman street with its medieval archways. Tickets via coopculture.it.
Official site →Deeper still, you can go caving through the guts of the Celio: an ancient tuff quarry plus several sunken ponds. From the entrance close to the Basilica dei SS Giovanni e Paolo, stairways descend into the core of the Tempio di Claudio and onward into the blackness of the workings, where passageways open onto the laghetti, the ponds, and onto chambers freckled with young stalactites and tiny organisms that glint like diamonds when your torch hits them. Keep an eye out for wells and for the vintage electric cables strung through the tunnels in their second career as bomb shelters in WWII. The quarry, probably worked for some 300 years before the 5th century CE, is toured by Roma Sotterranea at €12 plus a €5 ticket; the outing runs roughly ninety minutes. Book on visiteromasotterranea.it.
Cartography buffs will love this recently opened museum, devoted to a colossal 3rd-century map. The Forma Urbis Romae, displayed originally in Rome's Tempio della Pace, was a full city plan pieced together from 150 engraved slabs of marble, roughly 18 by 13 metres in size. About a tenth of it survives, and those fragments are now set into an 18th-century illustrated plan that covers the museum floor, letting you tread across the ancient street grid and pore over its astonishing detail. The museum crowns the Parco Archeologico del Celio, a compact archaeological park, free of charge, where finds from the area dug up during the 1800s are displayed.
Official site →In daylight, Via di San Giovanni in Laterano is every bit as touristy as its neighbours around the Colosseum. It falls away from the rear of the basilica, and its lower stretch is a string of cafes and restaurants where tired travellers grab a bite beneath the looming Flavian Amphitheatre. Nightfall changes the picture completely: the stretch nearest the Colosseum ranks among Rome's favourite gay hangouts, with bars such as My Bar and Coming Out quickly filling up and drawing mostly gay crowds that stay well into the small hours.
May Day rock-out: love Italian pop, or simply love a party? Then be in Piazza di San Giovanni on 1 May, when crowds running into six figures gather for Rome's free Primo Maggio concert. Headliners from the Italian scene, plus the odd international act, keep the jubilant crowd going through the afternoon and deep into the evening.
Baked goods and seasonal Italian plates are the draw at this well-known San Giovanni spot.
Laid-back Testaccio dining built on seasonal produce and first-rate ingredients.
Among the best bets on the touristy streets by the Colosseum.
A compact, friendly osteria sticking to Roman classics.
A busy Celio pizzeria, close to the Colosseum, turning out thin Roman-style pizza.
Stand in line for the archetypal Roman pizza: bare-bones room, gruff staff, razor-thin crisp bases.
Wood-fired pies, craft beer and an easy-going atmosphere in San Giovanni.
At Box 22 in Testaccio market, outstanding pizza by the slice with inventive, generous toppings.
The Aventino, with its rooftop gardens and swooning views, ranks among Rome's priciest residential addresses. Down below, Testaccio could hardly be more different: a one-time workers' quarter now humming as a foodie hub.
Among Rome's many showpiece viewpoints, the keyhole on the Aventino ranks with the city's most unforgettable sights. Climb to Piazza dei Cavalieri di Malta, an elegant 18th-century square whose ornamental facade belongs to the Villa del Priorato di Malta, and nothing seems to be on show until you press your eye to the keyhole of the villa's green door. Dead ahead, closing a tree-lined avenue, hangs the dome of St Peter's Basilica, dead-centre as if measured with a ruler. The effect is geometrically perfect and strangely hard to capture on camera.
Tip: Photographing the keyhole is fiddly: rest your phone flat against the door and try a few angles before the queue behind you grows impatient.
Also known as the Parco Savelli, this small walled park crowns the Aventino as a romantic haven: orange trees in blossom, tall stone pines, and swooning rooftop panoramas over towards St Peter's dome. Watch the cupola as you stroll: it seems to shrink the closer you walk towards the park's street-side edge, in apparent defiance of physics.
Tip: Few places beat it for watching the sunset: come late afternoon and stay for the changing light over the Vatican.
On the Aventino's verdant summit, this is a jewel of early Christian architecture, perhaps the loveliest church on the hill. It dates from the early 5th century and, although much modified since, preserves its original cypress-wood doors down the side, carved with 18 panels of biblical events. Check the upper-left panel: it holds one of the earliest Crucifixion images known, showing Jesus between the two thieves, strangely without their crosses. Inside, seek out the grave slab of Muñoz de Zamora, a founding father of the Dominicans.
The city's rose garden spills down the Aventino's flank, and every spring it explodes in colour as upwards of 1100 cultivars open their blooms. Garden lovers will want to see the prize entries grown for the Premio Rosa, the prestigious competition staged here each May. The site was once a Jewish cemetery, and the beds are arranged in the form of the menorah, the seven-branched candelabrum, as a tribute.
Beneath the curious gaze of Testaccio's odd pyramid, in truth a tomb from the 1st century BCE, spreads the non-Catholic cemetery, a green and restful oasis where you can happily while away an hour. Some 4000 non-Catholics lie buried here, their headstones tucked beneath umbrella pines and slim cypresses. The roll call includes Keats and Shelley, the two Romantic poets who each died in Italy; Andrea Camilleri, whose Inspector Montalbano series became bestsellers; and the Marxist thinker Antonio Gramsci. Among the graves, hunt down the Angelo del dolore, the 'Angel of Grief', a widely copied 1894 work that American artist William Wetmore Story made for his wife's resting place. Opening hours are on cemeteryrome.it.
Tip: Visit on a quiet morning: the silence under the pines, broken only by birdsong, is the cemetery's real gift.
Official site →For genuine cucina romana, Testaccio has no rival. The district's devotion to Roman cooking is legendary, and traditional trattorias turning out the city's classic dishes stand on every corner. The offal is the true signature of a Testaccio menu: Rome's whole nose-to-tail tradition was born here, when slaughterhouse hands found their wages padded with inexpensive cuts. Whether you mean to tuck in or steer clear, learn the vocabulary:
Inventive flavours and top-notch gelato; the Aventino scoop shop rarely lets you down.
A tiny San Giovanni gelateria scooping fine artisan ice cream into biscuity cones.
A historic Testaccio cafe famous for its cornetti (croissants) baked in-house, along with pastries and mini-tiramisu sweets.
A French-style patisserie turning out indulgent cakes, pastries and sweet things.
The Terme di Caracalla, sprawled at the Aventino's base, ranks with the most staggering ancient sites in Rome. The towering remains of Caracalla's early-3rd-century bathing palace testify to Roman engineering genius and to the sheer bulk of the imperial city. The ruins are clearly signposted and seldom crowded, which makes wandering them a genuine thrill.
Opened in 216 CE as the Thermae Antonianae, the complex stretched across 10 hectares and threw together gardens, libraries, gyms, shops and a full run of baths. As many as 8000 bathers a day passed through its doors, while deep underground an army of slaves, hundreds strong, kept the machinery running along 9.5km of service tunnels. Roughly 10 tonnes of timber went up in smoke daily to keep the water hot; it arrived via an aqueduct built for the purpose. The baths operated until 537, when the Visigoths severed Rome's water supply. After that the complex was stripped for construction stone and dug over repeatedly; the most famous excavations, commissioned in the 1500s by Pope Paul III, brought up major sculptures, several of which ended up in the Farnese collection and today hang in the Vatican collections and in Naples' Museo Archeologico Nazionale.
What stands today is essentially the central bath block: a vast rectangle flanked at either end by a palestra, or gym, and built around the frigidarium, the cool hall where bathers recovered after the tepidarium and the dome-topped caldarium, the hot room. After all that exertion, Romans unwound beside the natatio, its swimming pool framed by columns. You come in through the palestra occidentale, the western gym, then follow a wooden walkway across stretches of black-and-white geometric mosaic to the natatio, an Olympic-size pool ringed by space for ball games. Along the way, to your right while heading towards the eastern gym, the palestra orientale, notice the pitted marble slab known as the tabula lusoria: a gaming table for a lost Roman pastime called 'tropa', or 'the hole game'. A gravel track leads out of the eastern gym, swings back and re-enters the frigidarium, a mighty hall, once lavishly ornamented, that measures 58 by 24 metres and went on to shape structures as far afield as Chicago's Union Station or New York's original Pennsylvania Station.
Buried in the honeycomb of tunnels beneath the ruins lies Rome's biggest Mithraeum, uncovered in 1912 and restored around the start of the 2000s. One of a number of Mithras sanctuaries across the ancient city, it was where followers met for rituals revolving around a bull sacrifice. Access is limited to special events, so watch soprintendenza-specialeroma.it for openings.
Leading off the eastern gym stands the Domus di Vigna Guidi, freshly restored and dating from the 100s CE; part of it was demolished when the baths went up. What remains includes the sacellum, a household shrine, whose rare devotional frescoes pair Roman gods with Egyptian deities, a pairing that mirrors the way cults were converging across Rome back then.
When the ruins are done with you, amble across the lawns, where a pair of contemporary artworks wait. One of them, Lo Speccio (2024), whose name translates as 'The Mirror', is a big rectangular sheet of water built to mirror the ruins and toss light around with fountains along its sides. In the grounds' upper right corner, Il Terzo Paradiso (The Third Paradise, 2012) by Michelangelo Pistoletto traces an infinity sign made of three interlocking rings in the turf.
The Nuovo Mercato di Testaccio shows you how ordinary Romans shop and eat. On weekday mornings the market throbs with locals doing the daily shop: squeezing fruit, inspecting vegetables, browsing racks of wardrobe basics. When noon arrives, the spotlight swings to the famous food counters.
The market has occupied a purpose-built hall since 2012, planned by the architect Marco Rietti. Daylight pours through the glass roof of the white steel-and-panel structure, and terracotta cubes across the exterior walls echo the shattered amphorae heaped on nearby Monte Testaccio.
Roughly a hundred stalls radiate from a central bar zone, serving shoppers, students from the architecture faculty up the road, gourmets and holidaymakers alike. Count on everything from bread still warm from the oven and seasonal fruit and vegetables to kitchenware, shoes, dainty jewellery and artisan fashion. If you arrive with an appetite, the food stalls steal the show: Mordi e Vai (Box 15) fills rolls with meltingly soft slow-cooked beef, the panino con l'allesso di scottona; Food Box (Box 66) turns out crispy fried bites; Casa Manco (Box 22) slices superb pizza; and Da Corrado al Banco 18 (Box 18) pours regional wines alongside cheese.
A trattoria with a retro 1970s look that is now San Giovanni's hardest table to book, devoted to traditional Roman cooking.
A Testaccio favourite whose modern look hides a devotion to classic Roman comfort cooking.
A cult trattoria, master of the Roman classics and notably clever with foraged greens.
Built into the flank of Monte Testaccio, serving down-to-earth cucina romana.
A famous market stall packing panini with rich, meaty Roman fillings.
Natural Italian wines poured alongside cheeses at Box 18 of the market.
Veterans drop in for bread and chit-chat; visitors come for the pizza bianca, the oiled, salted flatbread.
The trapizzino was born here: a focaccia cone packed with fillings such as meatballs in sauce.
A guided climb up Monte Testaccio gets you to the very core of the district. Locals call it Monte dei Cocci: a grassy, man-made hill that is one colossal heap of broken amphora pottery, testae in Latin, which is where the name Testaccio comes from. From the 2nd century BCE until the 200s CE, the zone functioned as Rome's river port: olive oil landed in giant terracotta jars that, once drained, were smashed and piled beside the warehouses, eventually banking up a hill fully 54m high. Tour details are on 060608.it; tickets cost €4 for adults and €3 reduced.
Tip: The tour is short but wonderfully quirky: a stroll over Rome's ancient recycling heap, where amphora stamps and drainage channels are still visible.
Official site →For the best part of a century this complex was Rome's chief slaughterhouse. Since closing in 1975 it has been reborn as the Mattatoio, a contemporary-arts centre where cavernous halls host shows, installations and live performances from established and up-and-coming international artists; entry is free. In the adjacent pens, the graffiti-covered Città dell'Altra Economia runs festivals of its own, notably the May-time Spring Beer Festival with its 220 craft beers, live bands and street food. See springbeerfestivalroma.com.
Official site →Sleeping options here trade the centre's noise for calm and value. The Hotel Lancelot sits on the Celio, just back from the Colosseum; on the Aventino, the Althea Inn Roof Terrace, Hotel Sant'Anselmo, Sonder and The Corner Roma cover several styles and price points, while Testaccio offers fewer beds but a prime position for food lovers.
Plan around an hour once you clear the security check. Crowds are rare outside the main religious festivals.
Correct: the church itself is free, but the buried levels need an advance online ticket (€10 adult, €5 reduced), and you should set aside roughly thirty minutes below ground.
It joins most state sites in waiving the fee on a Sunday at the start of the month. Otherwise expect a ticket of around €12 when a temporary exhibition is on.
Ride metro line B to the Piramide stop: the market, Monte Testaccio and the Cimitero Acattolico are all within easy walking distance of the station.
Weekday mornings for the full local shopping scene. The food stalls are busiest between 12.30pm and 2pm, so go before or after to dodge queues.
Rome is the spiritual capital of the planet's 1.2 billion Catholics, and its churches keep you shoulder to shoulder with pilgrims from every continent: nuns from Nigeria, seminarians from Bulgaria, students from Notre Dame, Mexican families travelling in a pack, ordinary believers coming home to their faith. The pilgrim trade shaped the city after the empire collapsed. At its height ancient Rome held around 1.2 million people; when the barbarians cut the aqueducts in 476, the population fled and the Tiber's estuary silted up into marshland. Through the Dark Ages mosquitoes reigned over a shrunken village of 20,000, which was bad news for pilgrims and for the papacy alike. During the Renaissance the popes rebuilt Rome as a place fit for pilgrimage, and in the late 1580s Sixtus V reconnected the aqueducts and drove long, straight boulevards from one great church to the next, planting obelisks as signposts. A hardy walker can link the pilgrim churches on foot, roughly a mile and a half all told; the classic route starts at Santa Maria Maggiore (metro line A to Termini or Vittorio Emanuele, then seven minutes on foot), from where Via Merulana runs straight downhill to the Lateran, about twenty minutes away.
Pilgrims traditionally aim to cover four great basilicas: St Peter's, St Paul's Outside the Walls, Santa Maria Maggiore plus San Giovanni in Laterano; those two anchor the old pilgrim trail through this corner of the city. The Lateran impresses with sheer grandeur and history, and its Holy Stairs offer an experience found nowhere else; Santa Maria Maggiore and its neighbour Santa Prassede guard mosaics from Christianity's earliest years in Rome. Before setting out, check opening hours: San Clemente, Santa Prassede and the Holy Stairs all close for a long stretch at midday.
From across the piazza the monumental 18th-century facade reads like a billboard for the faith, with Christ triumphant on its crown. The bulky peach-coloured Lateran Palace next door occupies the ground where the popes' earlier residence stood, their home until around 1300. Low granite posts, only about a metre high, ring the church: cross them and you have left Italy for Vatican territory, where the carabinieri check their weapons at the entrance. Twin marble tablets flanking the central entrance announce that this is the church from which the whole Christian faith descends. Inside the portico, the tall bronze doors, green with age and patterned with acorns and flower scrolls, were salvaged from the Curia, the Senate House of ancient Rome; their transfer in the 1650s was a deliberate statement that the Church now wrote Europe's laws. Extra borders of stars were fitted later to make the doors look bigger, and the dainty acorns themselves are third-century originals.
As the first Christian basilica in Rome open to all worshippers, San Giovanni set the pattern every later church copied, St Peter's included. The floor plan, a broad central nave with an aisle on either side, comes straight from the ancient Roman basilica, the great hall where courts convened and crowds gathered, chosen because it could swallow a large congregation. Through the grand west portal the entire space opens before you at a glance, and the ranks of columns usher you towards the altar. Very little of the original building survives: for the 1650 Jubilee Pope Innocent X handed the interior to Francesco Borromini, who swept the nave into the Baroque and installed the colossal apostles striding from their niches as if hauling the heavenly Jerusalem down to street level. Above each statue a relief pairs an Old Testament scene on the left with its New Testament echo on the right; at the far back, Jonah climbing out of the whale faces Jesus rising from the tomb, two resurrections answering each other. The medieval marble floor and the Renaissance ceiling, which the pope insisted on keeping, were spared the baroque treatment.
In the left transept, four columns of gilded bronze carry a triangular pediment sheltering a bearded God the Father who could pass for Jupiter himself. Legend places them in the Temple of Jupiter, the holiest shrine of pagan Rome, which crowned the Capitoline Hill around 50 BCE; their presence here, holding up the God of the Christians, makes the point visible: the old gods have lost. In the apse, the carved cathedra, the bishop's throne, is a reminder that this is the city's cathedral and the pope its bishop: a fresh pope has to physically occupy this seat before he is properly pope, normally within a month of the election. Pope Francis did so on 7 April 2013. The mosaic above preserves a scheme first devised around 450, though the version on the wall dates from the 1200s and was given a heavy restoration in the 1800s: a cross rises among animals and plants, with the waters of the Jordan curling along the bottom edge, and the face of Christ gazing down from the cross's summit was surely a wonder to the first congregations: among the first lawful images of him that formerly pagan Rome ever saw.
Across the piazza, in an unremarkable building facing the basilica, pilgrims queue for the Scala Santa, the Holy Stairs. In 326 Constantine's mother, Helena, carried back from Jerusalem the 28 marble steps that once formed the staircase of Pontius Pilate's residence there, the same steps, so tradition holds, that Jesus mounted on the day his death sentence was passed. The treads are cased in walnut wood, dotted with small glass-covered openings said to show stains of Christ's blood, and every day hundreds of penitents go up on their knees, murmuring prayers as they climb. At the top waits the Sancta Sanctorum, the Holy of Holies, the popes' private chapel in the Middle Ages, reputed in its day to be the most sacred spot anywhere; in 1905 the relics were transferred to the Vatican. Visitors mount the side staircases free of charge and peer into the chapel through the grates; going inside costs €3.50, with tickets from the desk near the entrance, and the gift shop sits on the top floor, to the left. Feeling penitent? A €2 booklet sets out the right prayer for every one of the 28 steps. The stairs themselves are free, open every day from 6 in the morning to 2 in the afternoon and again from 3 to 7; the chapel keeps the same hours except that it shuts at 17:15 and stays closed all day Sunday.
Two more stops on the old pilgrim trail, both a short ride from the Lateran, preserve the atmosphere of the first Christian centuries: Santa Maria Maggiore, with its fifth-century mosaics, and Santa Prassede, where Byzantine gold glows in the gloom. Both are free, and both are easy to add to a Lateran morning.
The basilica honouring the Virgin Mary, mother of Jesus, was raised in 432, in the years when Rome was collapsing about its citizens. The Visigoths had sacked the city in 410, the last emperors would bow out in 476, and power increasingly passed to the popes, who took charge where the empire had failed. It ranks among the four major basilicas and, like the Lateran, stands on Vatican territory with the status of an embassy. Free entry, open daily 7am to 6:45pm. A statue shows Pope Pius IX on his knees before the church's great treasure; it was he who gave the Immaculate Conception the rank of official doctrine, and the treasure itself is a glass case holding an urn of wooden fragments bound with iron, said to be pieces of the manger, the animals' feeding trough, where the infant Jesus lay. In the piazza outside stands the column of Mary, one block of marble that once stood inside the Basilica of Constantine down in the Forum.
The church owes its existence to a snowfall in August. One hot night in 358 the Virgin came to Pope Liberius in his sleep, asking him to build her a church wherever snow would fall; the next morning, on 5 August, a patch of snow was found on the Esquiline Hill, and there the basilica was begun. The miracle is pictured in a bronze relief above the chapel's altar, where a pope shovels snow while astonished bystanders look on.
The church guards some of the best-preserved early Christian mosaics in the world, laid down in 435. Small square panels line the wall above the columns of the right aisle, telling Moses's story in surprisingly colourful, realistic scenes, far more sophisticated than anything Europe would produce for another thousand years: baby Moses plucked from the Nile, the burning bush, the flight from Egypt through the parted Red Sea while Pharaoh's troops drown, quail falling from heaven in the desert, the Ten Commandments, and Joshua bringing down the walls of Jericho. In the apse, a 13th-century mosaic crowns the whole: Mary, crowned by Jesus, sits beside him on a single throne, the two of equal size, borne aloft in a bubble of heaven by angels, while six saints stand below at half her height and a tiny pope, in red, kneels at the lower left. For the full tour of the basilica, including Bernini's tomb, see the Monti & Esquilino chapter.
A hundred yards from Santa Maria Maggiore, an unmarked doorway at the side leads into Santa Prassede, whose mosaics of 822 are the finest Byzantine-style work in Rome. Byzantium, as the eastern Roman Empire is called, kept its capital at Constantinople and never fell: its inhabitants preserved their Greek-speaking Christian way of life for ten centuries while the west groped through the Dark Ages. Byzantine artisans had kept alive the mosaic craft of ancient Rome, and now returned it to the city in its darkest hour. The interior is dim, so bring €1 coins for the light boxes and watch the gold come alive. The church is free, open daily 10am to noon and 4pm to 6pm, with no visits during Mass.
Tucked off the right-hand aisle, the chapel of Saint Zeno is the showpiece: an entire room encased in mosaic that medieval worshippers called the Garden of Paradise. The ceiling glitters gold, the Byzantine idea of heaven; Christ steps out of the background like an icon, held up by white-winged angels with painted rosy cheeks, perched on the columns, while saints wander through flowery meadows. Around the altar recess, Mary with the child Jesus keeps company with the two sisters, Praxedes and Pudentia; a figure whose square blue halo marks her as Theodora, the builder-pope's mother; and a side niche enshrines a fragment of the column against which Christ was scourged as he walked towards Golgotha.
In the curving half-dome over the high altar, Christ stands in a sky of coloured clouds, saints at his side, commanding Peter to carry the Good News to the world; beneath them twelve symbolic sheep file out of Jerusalem's gates to preach. The story continues at Peter's side: arriving in Rome, the persecuted apostle was sheltered by the sisters Pudentia and Praxedes, whose house stood on this very spot, which is why the church bears Praxedes's name. Far left stands a saint with the square halo that convention gave to people still living when the work was made: the figure is Pope Paschal I, the man who commissioned the church in the 800s as a memorial to the two sisters and engaged the most skilled mosaicists alive for the work. Paschal also emptied the endangered catacombs of the martyrs' bones, reburying them in churches safe within the walls.