Candlelight twinkling from gold chandeliers pierces the gloom in this functioning 8th-century church, modelled on its İstanbul namesake. The dome has a striking mosaic of the Ascension of Christ. Built over a previous 3rd-century church, it's notable for the cross-basilica style associated with middle-Byzantine architecture. The narthex and south aisle were used as a burial place for dignitaries from the 10th century. Like many Thessaloniki churches, it spent a period as a mosque (1535–1912) before returning to Christian worship.