The Monastery of St. Andrew in Krisei (now Koca Mustafa Pasha Mosque) was Byzantine church located on the seventh hill of Constantinople, north of Psamathia (Turkish Samatya) somewhat near the Cistern of St. Mocius and the Gate of Selymbria (Turkish Silivri Kapı).
The church has undergone significant changes since its conversion into a mosque, which have obscured most of its original character. While it probably had an ambulatory plan, it was reoriented by ninety degrees so that it would face toward Mecca. The southern aisle was transformed into a mihrab; its original barrel vault was replaced by a Turkish half-dome, and the original Byzantine dome was replaced by an Ottoman dome. A portico with five bays along the north wall of the building was also added during the Ottoman era. Several Byzantine capitals have survived, some of which perhaps date to the 6th century. Its entire exterior is encased in limestone, and the interior is plastered and painted, making its identification and the date of the budding are uncertain.
According to tradition, it was founded in the 8th century and dedicated to the iconophile St. Andrew of Crete who was martyred during the reign of Constantine V (741-775). It was also possibly restored during the reign of Basil I (867-886). Following the Latin occupation of Constantinople, it was significant renovated or even rebuilt by Theodora Raoulaina (ca. 1240-1300), niece of Emperor Michael Vlll Palaiologos. It was converted into a mosque by Koca Mustafa Paşa, the grand vizier of Bayezid II, in 1486. The mosque is also known as Sümbül Efendi Mosque, who establish a tekke (a dervish lodge) on site. The mosque complex also includes the tombs of several saints, a madrasa and a soup kitchen.
Istanbul Archaeological Museums
Architecture and Ritual in the Churches of Constantinople: Ninth to Fifteenth Centuries by V. Marinis
Converted Byzantine Churches in Istanbul: Their Transformation Into Mosques and Masjids by S. Kirimtayif
Bildlexikon zur Topographie Istanbuls: Byzantion, Konstantinupolis, Istanbul by Wolfgang Müller-Wiener
Byzantine Churches of Constantinople (Byzantine Legacy Google Map)