under the ground.

"Yerebatan Sarai is the most unusual place I have ever seen. Most of the time it is empty, but I happened to be there when it was decorated and magical music was playing. Built in the 6th century, it's the largest of several hundred cisterns that lie beneath the city of Istanbul, Turkey. Cisterns were typically used for water storage, and Yerebatan Sarayi once provided water for the Great Palace of Constantinople." - magda biskup