Harran Castle stands out separately from its usual architectural features. Although among the information obtained in three different periods, the only fact is that the structure with dotecagon towers reveals perfection. Research on Harran Castle has revealed that it has been replaced by additions and repairs in three different periods. In 1059, inscription describes the first period mention about named after The King of the Numeyri, Meni. In the eastern part of the castle, a horse shoe shaped arche structure was uncovered from basalt stone. During the Melik El Adil period, i.e. in 1059, additions were made in the western part of the castle. Here, a niche with galleries and fountains and large mosque with crib vaults, has reached the present day. Finally, it draws attention to the inscription on the walls on the southern façade of the castle. It appears that the inscription belongs to El Nasr and was written in 1315. Sources for Harran Castle, southeast of Harran, say there is a Sabi-i Mabedi in this place. In fact, in an Islamic source, it describes the castle being made of stone like the Fortress of Jerusalem in the 10th century. However, the most surprising information is also obtained from Islamic sources.It is seen that the palace built by Marwan II The Umayyed Caliph by spending 10 million dirhams constitutes the true structure of the castle. As of the building, the castle, which is 90x130 meters in size, was built in three floors.There are a tower made of dotecagon all four corners of the irregular rectangular planned castle.