Hagia Irene
Eminönü, Turkey · built 350
Hagia Irene or Hagia Eirene (Medieval Ἁ ἰ Ancient Greek pronunciation: [aˈʝia iˈrini], "Holy Peace", Aya İrini), sometimes known also as Saint Irene, is a former Eastern Orthodox church located in the outer courtyard of Topkapı Palace in Istanbul. It is the oldest known church structure in the city and one of only two Byzantine churches still standing in Istanbul today that were never converted into mosques, alongside the Church of Saint Mary of the Mongols, as it was used as an arsenal for storing weapons until the 19th century. The Hagia Irene now operates as a museum and concert hall.
Church data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).