The Basilica Cistern (Byzantine Greek: βασιλική κινστέρνή; Latin: Basilica Cisterna) is the city's largest indoor cistern, located on the European side of Istanbul. It is entered from a small building to the southwest of the Hagia Sophia building. The ceiling of the place, which has the appearance of a column forest, is brick-built and cross-vaulted.

The cistern was built by the Byzantine emperor Justinian I (527-565). Due to the many marble columns rising from the water, it is called the Basilica Palace among the people. The building is also called Basilica Cistern because there was a basilica in the place where the cistern is located. Also, the cistern has been the subject of Dan Brown's novel Hell.

Currently, one of the affiliates of Istanbul Metropolitan Municipality, Kültür A.Ş. Basilica Cistern, operated by Basilica Cistern, hosts many national and international events as well as being a museum.