This unknown Middle Byzantine church was located in the northwest corner of Constantinople, just within the Heraclian Walls. The Church of Panagia Blachernai and Atik Mustafa Pașa Mosque are located south and southeast respectively.  
The church was a single-nave structure measuring approximately 14 x 7 meters. It had a single apse flanked by two shallow niches on its eastern walls. A wide dome covered its square naos which was preceded by a narthex. Fragments of fresco decoration, dating to the fourteenth century, included busts of saints (including St. Hagia Eleutherios, Aberkios, Polycarp, Spyridon, Prokopios and Niketas) and the Nativity in the sanctuary were recorded before its destruction. It has frequently been identified with the Church of St. Thekla, which was located in the confines of the Blachernai Palace. Supposedly converted into a mosque by Toklu Ibrahim Dede, it was the location of Ebü Seybet-ül-Hudri, a companion of the Prophet Mohammed who was killed during the Arab siege of Constantinople.
It was largely destroyed in 1929, leaving only part of its apse and south wall. At this time, a large number of stamped bricks were recovered, evidently reused materials of the fifth and sixth centuries. Its construction techniques suggest that it was built around the eleventh century.