The Church of Saint Panteleimon is a late Byzantine church in Thessaloniki and a UNESCO World Heritage Site.
The church lies in the eastern part of the old city, near the Tomb of Galerius, at the junction of Iasonidou and Arrianou streets. Its current dedication to Saint Panteleimon was given to the church after the end of Ottoman rule in 1912, and its original dedication is therefore disputed. In Ottoman times, it was converted into a mosque in 1548 and became known as Ishakiye Camii, which in the prevailing scholarly interpretation points to an identification with the late Byzantine Monastery of the Virgin Peribleptos, also known as the Monastery of Kyr Isaac after its founder Jacob, who was the city's metropolitan bishop in 1295–1315 and became a monk with the monastic name of Isaac.
A counter-argument however supports the theory that the present church is unrelated to the Peribleptos Monastery, and that it was converted into a mosque ca. 1500, when the city's kadı (judge), was Ishak Çelebi, whom the mosque was named after. However, the church's architecture and decoration, which date to the late 13th/early 14th centuries, appear to support the former view.
The church is of the tetrastyle cross-in-square type, with a narthex and a (now destroyed) ambulatory that is connected to two chapels (still extant). Very few of the building's original wall paintings survive. Ottoman remains include the base of the demolished minaret and a marble fountain.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.