Basilica Cistern : The Basilica Cistern, is the largest of several hundred ancient cisterns that lie beneath the city of Istanbul, Turkey. The cistern, located 500 feet southwest of the Hagia Sophia, was built in the 6th century during the reign of Byzantine Emperor Justinian I. More here.

Canon EOS 7D | Length: 17 mm | Aperture: f 5.6 | Shutter: 1/3 sec | ISO: 1600