The church of Agios Giannis the Baptist is an early Christian Baptistery built in the 5th or 6th century AD. The temple is located inside the cemetery of the city and today it functions as the cemetery church of the city of Kos. It is perhaps the only early Christian Baptistery surviving to this day.
The building was surrounded by wide, vaulted corridors, from which only the foundations remain today. On the outside it is shaped as a rectangle, while on the insied it has a circular shape, with four alcoves in its four corners and one in the middle of its eastern side. However its walls form 8 dents, together with one to the west, 7 of which resemble altars (Bemas) of the eastern orthodox churches. This is why the temple is known as the "Seven Bemas" church.
Recently in the temple frescoes dated to the 12th or 13th century have been uncovered, portraying scenes from the life of the Saint.