| Sancaktar Hayrettin Mosque Sancaktar Hayrettin Câmîi | |
|---|---|
 The mosque viewed from the north | |
| Religion | |
| Affiliation | Sunni Islam |
| Year consecrated | Shortly after 1453 |
| Location | |
| Location | Istanbul, Turkey |
  Location in the Fatih district of Istanbul | |
| Geographic coordinates | 41°00′09.90″N 28°56′04.80″E / 41.0027500°N 28.9346667°E |
| Architecture | |
| Type | church |
| Style | Byzantine |
| Completed | 14th Century |
| Specifications | |
| Minaret(s) | 1 |
| Materials | brick, stone |
Sancaktar Hayrettin Mosque (Turkish: Sancaktar Hayrettin Câmîi; also Sancaktar Hayrettin Mescidi, where Mescit is the Turkish word for a small mosque, or Sancaktar Mescidi) is part of a former Eastern Orthodox monastery converted into a mosque by the Ottomans. It is generally believed that the small building belonged to the Byzantine Monastery of Gastria (Greek: Μονῆ τῶν Γαστρίων, Monē tōn Gastríōn, meaning "Monastery of the Vases"). The edifice is a minor example of Palaiologan architecture in Constantinople, and is important for historical reasons.