The Church of Saint Demetrios is located in Thoknia, on the southern side of the modern Church of the Annunciation. It belongs to the type of single‑aisled, barrel‑vaulted churches and is built of rough stone masonry with lime mortar. An exception to this construction are the carefully carved blocks at the corners and around the openings, which originate from ancient buildings. Inside, the semicylindrical vault is reinforced with two arches, while a later wooden templon of the 19th century is preserved. The interior is fully covered with wall paintings by the Pediotes painters Michael and Ioannis. The iconographic program is arranged in zones and depicts scenes from the Christological and Marian cycles, as well as episodes from the Old Testament. According to a dedicatory inscription, the church and its frescoes date to 1729, with Athanasios Koulopoulos recorded as the donor. Conservation and restoration works have been carried out on the monument.