The Basilica Cistern is one of Istanbul's most surprising tourist attractions. This huge, palace-like underground hall, supported by 336 columns in 12 rows, once stored the imperial water supply for the Byzantine emperors. The project was begun by Constantine the Great, but finished by Emperor Justinian in the 6th century. Many of the columns used in construction were recycled from earlier classical structures so feature decorative carvings. The most famous of these are the column bases known as the Medusa stones in the northwest corner with their Medusa head carvings. A visit here is very atmospheric with the columns beautifully lit and the soft steady trickle of water all around you.
Official site: http://yerebatan.com/
Distance from Our Hotel: 3-5 minutes by walking
The Museum is open in between: 09:00 to 17:30 every day
Entrance Fee: 20 TL