The Basilica Cistern, known as Cisterna Basilica, is the largest among the several hundred ancient cisterns that lie beneath the city of Constantinople (modern-day Istanbul), Turkey. Located 150 meters (490 feet) southwest of the Hagia Sophia on the historical peninsula of Sarayburnu, this impressive structure was built in the 6th century during the reign of the Byzantine Emperor Justinian I. Nowadays, it contains a minimal amount of water, allowing the public to explore its interior.
The term “Basilica Cistern” originates from its location beneath a large public square known as the Stoa Basilica on the First Hill of Constantinople. Prior to the cistern’s construction, a magnificent basilica, built between the 3rd and 4th centuries during the Early Roman Age, stood at this site. This basilica functioned as a commercial, legal, and artistic hub and was reconstructed by Illus following a fire in 476.
Ancient texts reveal that the basilica featured gardens, encircled by a colonnade, and faced the Hagia Sophia. According to historical accounts, Emperor Constantine initially constructed the structure, which was later rebuilt and expanded by Emperor Justinian after the Nika riots of 532 that caused widespread destruction in the city.
It is recorded that 7,000 slaves participated in the construction of the cistern. The expanded cistern served as a water filtration system for the Great Palace of Constantinople and other edifices on the First Hill. After the Ottoman conquest in 1453, it continued to supply water to the Topkapı Palace and has remained functional into modern times.
