Basilica Cistern: Ancient columns and arches reflected in illuminated underground water.

Visitors explore the awe-inspiring depths of the Basilica Cistern (Yerebatan Sarnıcı) in Istanbul, Turkey. This monumental underground water reservoir, commissioned by Byzantine Emperor Justinian I in the 6th century, was built to supply water to the Great Palace of Constantinople and nearby structures. Today, its 336 ancient marble columns and vaulted brick ceilings are dramatically illuminated and reflected in the shallow, clear water, offering a unique glimpse into Byzantine engineering and history.