Inside, the church is divided by two rows of large stone columns. The apse overlooks the Fountain Courtyard below and was flanked by two staircases that led up to it from the Courtyard. Note the well-preserved pulpit for the priest; pieces of carved marble plates that probably decorated it were found here.

Two chapels were later added to the church, one to the north and one to the south, as well as a baptistery. The baptistery is quite well-preserved and consists of a niche that may have been the waiting room, which led to the baptism room, and then an exit. This system would have allowed for more than one person to be baptized at a time.

The church was apparently being refurbished when it was destroyed by the earthquake in 749 AD.
(From information on site)