Kayseri Castle and Walls, which were built in the Roman period in the 3rd century and collapsed in the Byzantine period in the 6th century, was rebuilt in to what it is now in the time of Seljuk Sultan Alaeddin Keykubat I. Karamanoğulları and Osmanoğulları were repaired twice.The fortress, which protects the city center of Kayseri, which is located on the transportation passages in Central Anatolia, is a medieval castle with its old existence and its annexes made in time.
The historic city of Kayseri and its fortress is built on a flat and consists of two parts. The Inner Castle has been built as a separate castle with the fact that it was built higher than the Outer Castle and the fortifications attached to it.The outer castle covers the outer city walls and towers, the protection of the city, the administrative center and generally the settlement area.
"Ok Bastion" and "Yoğun Bastion" of norther nouter castle , which was made by I. Alaadding Keykubat and surrounding The Seljuk State House, survived to the present day. The iner fortress was extensively changed during theT urks period, and the surrounding walls and bastions and the gate towers were up graded and changes were made.Since there was no need to defend the city during the Ottoman period, neighborhoods were built in the iner castle and the existing Fatih Mosque was built during this period.