Kalenderhane Mosque - Credit: Wikimedia Commons
Kalenderhane Mosque () is a former Eastern Orthodox church in Istanbul, converted into a mosque by the Ottomans. With high probability the church was originally dedicated to the Theotokos Kyriotissa. The building is sometimes referred to as Kalender Haneh Jamissi and St. Mary Diaconissa. This building represents one among the few extant examples of a Byzantine church with domed Greek cross plan. Read more on Wikipedia
Source: en.wikipedia.org