Binbirdirek Cistern - Cistern of 1001 Columns also known as Cistern of Philoxenos is the second largest underground cistern in ancient Constantinople (after the Basilica Cistern), perhaps dates to the period of Constantine the Great, who founded New Rome (Constantinople) in 330 AD. It is situated between the Forum of Constantine and the Hippodrome of Constantinople in the Sultanahmet. The 212 columns (originally 224), each 14 to 15 meters tall, are made of marble from nearby Marmara Island. The cistern was restored by Justinian I during his renovatio imperii, in the 6th century.
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