Medusa Head, Byzantine Basilica Cistern, Sunken or Underground Palace, Sultanahmet, Istanbul, Turkey, Europe

Interior of Basilica Cistern, Sultanahmet, Istanbul, Turkey, Europe

Basilica Cistern with green illumination, Istanbul, Turkey, Europe

Basilica Cistern with an orange illumination. Istanbul, Turkey, Europe

Basilica Cistern with an orange illumination, Istanbul, Turkey, Europe

Basilica Cistern, Sultanahmet, UNESCO World Heritage Site, Fatih District, Istanbul Province, Turkey, Europe

Basilica Cistern columns, Istanbul, Turkey, Europe

Water reflecting columns at Basilica Cistern (Sunken Palace) subterranean water system underground, Istanbul, Turkey, Europe

Yerebatan Saray, underground cistern, Istanbul, Turkey, Europe

Subterranean Naples, part of an ancient Greek underground water cistern system, now open to tourists, Campania, Italy, Europe

Monumental head of a medusa, upside down, Yerebatan Sarayi, Byzantine cistern, Sultanahmet, Istanbul, Turkey

Entrance to Mycenae water cisterns for underground water storage, Mycenae Archaeological Site, UNESCO World Heritage, Peloponnese, Greece, Europe

Monumental head of a medusa at the foot of a column, Yerebatan Sarayi, Byzantine cistern, Sultanahmet, Istanbul, Turkey

Basilica Cistern is a huge underground Roman water source held up with 336 marble columns, on some of them Medusa heads and decorations covering 9, 800 sq. meters, Istanbul, Turkey

Yerebatan Sarayi Cistern, Istanbul, Turkey

Tourists at Medusa in Yerebatan Sarayi Cistern, Istanbul, Turkey

Tourists at Yerebatan Sarayi Cistern, Istanbul, Turkey

Tourists at Yerebatan Sarayi Cistern, Istanbul, Turkey

Yerebatan Sarayi Cistern, Istanbul, Turkey

Tourists at Yerebatan Sarayi Cistern, Istanbul, Turkey