Basilica Cistern (Yerebatan Sarayi) (Sunken Palace), Istanbul, Turkey, Europe

Yerebatan Saray, underground cistern, Istanbul, Turkey, Europe

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

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 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