Two monuments frame the ancient world's greatest empire at two decisive moments: the Colosseum, opened as Roman power was peaking, and Ponte Milvio, where a single battle in 312 CE set Christianity on the road to triumph.
Last updated August 23, 2026
In a nutshell: the Colosseum, opened by Titus in 80 CE, is the defining image of the empire's golden age, when Trajan ruled an empire that ran from Britain to the Middle East; Ponte Milvio, by contrast, marks the twilight of that pagan world - there in 312 CE Constantine defeated Maxentius, legalised Christianity the following year and funded the first great church-building campaigns. The history overview starts the story; Christian Rome continues it, while Foundations looks back to the beginning.
Nothing says blood and thunder quite like the Colosseum; no other monument sums up ancient Rome so vividly. The fearsome amphitheatre was opened by Titus in 80 CE, just as the empire's military might was peaking. Trajan (r. 98 to 117 CE) pushed the frontiers to their widest extent: Britain anchored the north, north Africa the south, Hispania the west, and Syria and Palestine the east.
The city of Rome counted some 1.5 million inhabitants and gleamed with everything imperial splendour required: marble temples, baths for the masses, theatres, circuses and forum after monumental forum.
Around the start of the 4th century the empire was in serious trouble. Diocletian, who ruled from 284 to 305, had divided the realm into two halves, east and west, in an effort to revive the economy and put an end to the internecine fighting - but the killing went on regardless, as would-be emperors battled for the throne.
The western half reached its decisive turning point in 312 CE. There Constantine faced Maxentius at the Milvian Bridge and won, a victory that opened the door for Christianity: he made the religion legal in 313 and underwrote a string of significant church-building campaigns.