Citadel, located in the southeastern part of the city, constitues that part of the rampart.
Almost all documents mention about a Sabian temple in the area of the castle. Mukkadesi, who referred to the castle in Islamic documents in 10. Century, stated that this castle was great, durable and made of stone like Jerusalem Castle.
Evliya Çelebi, who visited Harran in the mid XVII. century, quoted that “we had arrived to Haran Castle after 9 hours of travel to the south part. Nimrud built that castle as well. It was a dreable castle in the middle of the desert. It had a shape of pentagon and was made by a master”.
There are towers on each corner of the dodecagon on the irregular rectangle plan of Harran Castle. The tower on northwest collapsed completely. The outer section of the tower on the southeastern part collapsed and the inner still stands. The towers on southwest and northeast stand partly.