This cistern was built by Justinian I, just after the bloody Nika Revolt in 532. It was named Basilica Cistern as it was located underneath the Stoa Basilica, where the city’s law courts were situated. Throughout the Byzantine period, the cistern was used to supply water for the Great Palace and several other buildings. In Turkish, the cistern is called “Yerebatan Sarayı”, which means the Sunken Palace. In fact, it resembles an underground palace. A century after the Conquest of Constantinople, the existence of the cistern had fallen to oblivion until it was rediscovered, in 1546, by the French traveller Pierre Gilles. It would be used from then on for the water supply of the royal gardens in the Topkapı Palace.