The Church of St Demetrius of Thessaloniki is a mediaeval Bulgarian Orthodox church in the city of Veliko Tarnovo in central northern Bulgaria, the former capital of the Second Bulgarian Empire. The church lies at the northeastern foot of the Trapezitsa and Tsarevets hills, on the right bank of the Yantra River, outside the city's mediaeval fortifications. Architecturally, it has a pentahedral apse and a cross-domed design with a narthex and a fore-apse space. It was once part of a large monastery and belonged in its southeastern part. The church's exterior is decorated with blind arches and colourful ornaments: glazed rosettes, suns, rhombs and other painted figures. The church was built of stone alternated with three rows of bricks. It is 15.75 by 8.40 metres in size.