Pammakaristos Church

The Pammakaristos Church, also known as the Church of Theotokos Pammakaristos (ἡ, "All-Blessed Mother of God"), is one of the most famous Byzantine church buildings in Istanbul, Turkey, and was the last pre-Ottoman building to house the Ecumenical Patriarchate. Converted in 1591 into the Fethiye Mosque (Fethiye Camii, "mosque of the conquest"), it is today partly a museum housed in a side chapel or parekklesion. One of the most important examples of Constantinople's Palaiologan architecture, the mosque contains the largest quantity of Byzantine mosaics in Istanbul after the Hagia Sophia and The Chora. The mosque-museum is in the Çarşamba neighbourhood of the Fatih district inside the walled city of old Istanbul.

Mosque data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).