During the Byzantine era, underground waterways were used as reservoirs for water storage for the Great Palace and other main buildings. The “Sunken Palace”, better known in Turkish as “Yerebatan Sarayi”, is quite an authentic place. In theory, it is nothing else but a gigantic cistern : made up of no less than 336 different columns, it is a completely renovated, 132m long building located under the very popular Sultanahmet square. It is obviously very dark in the basilica cistern but the few lights allow for great pictures provided you find the right spot and succeed in getting away from the invading tourists. I will post other photos of Istanbul shortly so stay tuned!