From the site I quote from:

In the 5th/6th century, a Christian sacral complex was erected on the western terrace instead of the market basilica from the Roman Empire, thus clearly demonstrating the increase in ecclesiastical power in the centre of the city. "Characteristic is the ruthless seizure and conversion of old 'pagan' building sites. (Weber, p. 81) The columns, capitals and other elements come from the former buildings.

target=_ blank" >For a clear view of the area covered use the map view.