- Period
- Contemporary with the church
- Where
- About 300 m south of the southern façade
- Plan
- Square, with a small octagon at the centre
- Font
- A rectangular basin at the base of the eastern apse
The second building in importance after the church, put up at the same time, about three hundred metres south of its southern façade.
Parts of it repeat the church in construction and plan, particularly the octagon and the way it was roofed — the baptistery restates the church idea at a smaller size.
It is a square building with a small octagon at its centre, and on the eastern side an apse with a rectangular basin cut into the floor at its base for the baptism itself. Three arcaded galleries surround the octagon on the north, east and west.
On the southern side stands a small basilica-plan church whose walls are structurally separate from the baptistery — which shows it was built later. To either side of it are two rooms: the martyrion to the south, and to the north a service room for the liturgical vestments.
This is a baptistery for adults, and that says something about the place: people came here to be baptised themselves, not to bring children. They arrived grown, and were changed here.