Aspar Sarnıcı, Çukurbostan

The Cistern of Aspar — known in Turkish as Çukurbostan, meaning 'sunken garden' — is one of the last surviving open-air Byzantine water reservoirs in Istanbul. Built in the 5th century AD, likely during the reign of Arcadius or Theodosius II, it formed part of Constantinople's vast hydraulic network that channeled water from Thrace across dozens of kilometers into the imperial capital. The reservoir's name is traditionally linked to Aspar, the powerful magister militum of the Eastern Roman Empire, though the exact attribution remains debated by scholars. Its rectangular basin measures roughly 152 by 152 meters and today lies sunken into the dense urban fabric of the Fatih district, invisible from street level until you reach its edge and find a broad green depression where water once stood meters deep. Visiting alongside the nearby Yavuz Sultan Selim Mosque, the cistern reads as a quiet, almost accidental fragment of Byzantium swallowed by the modern city.