Yerebatan Sarayi means as the Cadaverous Palace is the grandest underground reservoir that showcases the remnants of the Romans. At present, this is one of the chief attractions in Turkey. Yerebatan Sarayi has a huge subversive storage reservoir built by Constantine the Great during the 4th century. For most of the Ottomans, the reservoir only served as a well and a fishing hole for the locals which are now the Sultan Ahmet. It became a mud-spattered empty ruin until it was cleaned up and opened to the public in 1987. Yerebatan Sarayi is a basilica sized subversive cistern which is 143 by 65 meters and can house up to 80,000 cubic meters of water.