Zeyrek Mosque (Pantocrator)

The Zeyrek Mosque complex is the second-largest surviving Byzantine religious structure in Istanbul after Hagia Sophia, predating the conquest by 300 years. The complex consists of two churches and a chapel built between 1118-1136 as the Monastery of Christ Pantocrator (and the imperial mausoleum of the Komnenos dynasty), originally a Pantokrator and a Theotokos church flanking a shared courtyard, with a smaller memorial chapel between them.

After the conquest, Mehmed II added the wooden minarets and the complex became a medrese. Today both churches function as a single mosque, but you can still see clearly the two parallel naves, the crossing domes, and the gold-ground mosaics and patched-up frescoes that survived the iconoclastic periods and the plastering-over of the Ottoman era.

The complex is in the Zeyrek neighborhood, uphill from the Valens Aqueduct and a 15-minute walk from the Süleymaniye. It was added to the UNESCO World Heritage tentative list in 2016 and has been the subject of major restoration work since 2019 — visit before any restoration closes it again for a few years.

The atmosphere inside is unusual among Istanbul mosques: dark, layered, the bones of three churches still visible. Free entry, modest dress, closed during prayer.