Legend. Aeneas is supposed to have settled here when he arrived from Troy.
495 BC. On these marshlands stood a massive Roman altar and Temple to Hercules.
69-81 AD. Under the Flavian Emperors a columned hall was built for inspectors of the nearby grain, fruit and vegetable market. They checked to make sure that customers did not get cheated. Next door was a stable of pureblood racehorses for the chariot races in Circus Maximus. Also a Temple to Mithras where charioteers could pop in for a prayer before the race.
200. A tiny chapel below ground thought to be part of the foundations of the temple (now the crypt) was built for Christians who risked death worshiping here during harsh regimes.
6C. A small church was erected for Rome's Greek population.
772. Pope Hadrian I enlarged and beautified the building for the flood of refugees from Constantinople escaping the iconoclastic persecutions (when Byzantine church authorities forbade worship of images).
1223. Restored again, including the floor which was redone, perhaps the first Cosmati floor.