The church of Saint Kyriaki (Agia Kiriaki) is located on the banks of the river Mouselas, fed by the rich springs of Argyroupolis. It is the result of the conversion of a late Roman bath to a church in the 9th century. The temple occupies the main area of the bath, which was built of bricks, and has been expanded by the addition of the arch of the sanctuary.
Newer tombs and bath remains have been discovered inside the temple, while a wooden platform has been placed on the floor to allow the visitors to wander over the lower parts of the ancient bath where hot air was passing.
The walls of the church have been painted in three phases (9th, 11th and 13th centuries) and are samples of exquisite hagiographic techniques with intense renewal tendencies for their time. In the sanctuary we can see Deesis with Christ on a large scale, accompanied by Theotokos (Our Lady) and Saint John the Baptist, frontal saints and hierarchs, while in the arch we see the Ascension following the Comnenean style.