The first building on this site was a Roman bath, followed by a sixth-century (the dating was based on precise coin finds in stratigraphic excavation) hall church with an apse laying up against the Aqueduct of Valens. Later – possibly in the seventh century – a much larger church was built to the south of the first church. A third church, which reused the sanctuary and the apse (later destroyed by the Ottomans) of the second one, can be dated to the end of the twelfth century, during the late Comnenian period. It may date to between 1197 and 1204, since Constantine Stilbes alluded to its destruction in a fire in 1197. The church was surrounded by monastery buildings, which disappeared totally during the Ottoman period. After the Latin conquest of Constantinople, the building was used by the Crusaders as a Roman Catholic church, and partly officiated by Franciscan clergy.