This 10th-century monastic church, dedicated to the Immaculate Mother of God, was founded by Constantine Lips Dungarios, a commander of the Byzantine fleet. Following the Byzantine reconquest of the city in 1261 , Empress Theodora, wife of Michael VIII Palaeologus . added a second church. She also commissioned a funerary chapel, where she and her sons were buried.

This unusual history has given the structure its present rambling appearance. In an idiosyncratic touch, there are also four tiny chapels perched on the roof around the main dome. Another highlight is the building's eastern exterior wall. This is decorated with a tour deforce of brick friezes, of the kind that are a hallmark of Byzantine churches of this period. When the church was converted into a mosque in 1496, it adopted the name Fenari isa, or the Lamp of Jesus. This was in honour of isa (Turkish for Jesus), the leader of a Sufi brotherhood who worshipped here at that time. Inside the mosque, which is still in use today, there are some well-restored capitals and decorated cornices.