5. Basilica Cisterns of Istanbul
The cistern was built in 532 AD by the Byzantine emperor Justinian I to store freshwater for the palace and the nearby buildings. The name Yearbatan Sarayi, or “The Sunken Palace” in Turkish. Is known in English as the “Basilica Cistern” because of its location on the site of an ancient basilica.
As Constantinople was building the cistern, Constantinople was still in the shadow of the devastating Nika revolt that took place in January of the same year. Restorations in the late 1980s dredged up the silted-up floor and added lighting, elevated walkways and a café for visitors. There are still fish in now-shallow water, which helps to keep the water clear.