Legend. Aeneas is supposed to have settled here once he arrived from Troy.
495 BC. On these marshlands stood a massive altar and Temple to Hercules.
69-81 AD. Under the Flavian Emperors a columned hall was built for inspectors of the grain, fruit and vegetable market (Forum Holitorium) just outside. They checked that customers did not get cheated. Nearby was the stable of thoroughhbreds for the chariot races in Circus Maximus. Also a Temple to Mithras where charioteers could pop in for a prayer before the race.
200 AD. A tiny chapel below ground, thought to be part of the foundations of the temple (now the crypt), was built for worshippers who risked death to come here.
6C. A small church was erected for Rome's Greek population.
772. Pope Adrian I enlarged and beautified the building, for the flood of Byzantine refugees from Constantinople escaping the Iconoclastic persecutions (when worship of images was forbidden).
1223. Restored again, and the floor redone, perhaps the first Cosmati floor.