Why go
This is a site to read through structure rather than intact decoration. The piers, columns and eastern apse show how builders turned a tomb shrine into a monumental church with a sequence of domed spaces. The surviving footprint becomes a map of the vanished roof.
The full story
An earlier basilica stood over the traditional tomb, but Justinian’s sixth-century replacement expanded the church dramatically. Its plan formed a Greek cross, with the central crossing and arms covered by domes. Heavy piers and marble columns carried the roof, while shorter vaulted sections joined the domed bays. The building also had a large eastern apse, giving the liturgical end a strong focus. Materials and workmanship came from more than one place: the account describes marble elements from Constantinople or Proconnesus and work by Ephesian craftsmen following metropolitan models. Later rulers added decoration. Most of the domes and their mosaic surfaces are gone, so the church may initially seem like scattered masonry. Walk the central axis, then look across the arms of the cross; the surviving supports make the lost volume more legible than a single view from outside.