Agia Ekaterini, Byzantine church in Upper Town, Greece

Agia Ekaterini is a late Byzantine church in the northwestern corner of Ano Poli, Thessaloniki, in the Tsinari area. It is a cross-in-square structure with a central dome, and fragments of its interior decoration survive from around 1315. The building is one of fifteen Thessaloniki monuments inscribed by UNESCO in 1988.

Agia Ekaterini dates to the Palaiologan period, though its exact date and original dedication are unknown. Fragments of interior decoration dated to about 1315 suggest it served as the katholikon of the Monastery of the Almighty. Under Sultan Bayezid II (r. 1481–1512), Yakup Pasha converted it into a mosque bearing his name, Yakup Pasha Mosque.

The church is known locally as Agia Ekaterini, though its original dedication is unknown; the 1315 fresco fragments suggest it served as the katholikon of the Monastery of the Almighty. Under Ottoman rule it became the Yakup Pasha Mosque, named after the pasha who converted it. The building now belongs to the UNESCO listing of Thessaloniki's Paleochristian and Byzantine monuments, inscribed in 1988.

The church sits near the Byzantine walls on Olympiados Street and is easy to spot from the outside. Visitors should know that opening hours can vary, so it helps to check ahead before planning a visit.

The building stands out for its use of brightly colored marble elements, which is uncommon for churches from this period. These colorful details give the interior and exterior a special look that you rarely see in other Byzantine structures around the city.