Hagia Eirene (Basilica of Holy Peace, Turkish: Aya Irini Kilisesi) stands on what is thought to be the oldest place of Christian worship in Istanbul. Today it is located within the Topkapi Palace complex, close to the Hagia Sophia.
The first church to stand on this site was built by Constantine along with Hagia Sophia and the Church of the Holy Apostles. The present church dates from the 6th century.
Within a decade of the Ottoman conquest of the city in 1453, Hagia Eirene had been incorporated into the Topkapi Palace and used (perhaps ironically, given the name) as an arsenal. It was one of very few former Byzantine churches not to have been turned into a mosque.
Today Hagia Eirene, which has excellent acoustics, hosts concerts during the Istanbul Music Festival.
What to See
Hagia Eirene is well worth seeing, as it preserves several interesting features not seen in Istanbul's other Byzantine churches. In the apse are the synthronon, five rows of built-in, theater-style seats for use by clergy during services.
In the apse itself is a large mosaic of a simple black cross on a gold background, dating from the iconoclastic period in the 8th century, when all figurative images were forbidden.
In the back of the church is a cloister-like courtyard where deceased Byzantine emperors once lay in their porphyry sarcophagi. Most of these have been moved to the Istanbul Archaeological Museum.