This huge basalt citadel has stood in the heart of Kayseri since the 13C. Its warlike appearance, blocks of lava, and 19 towers dotted around the rampart walk make this one of the most impressive examples of medieval architecture in Turkey. Cunning defensive systems were developed here, such as the 30m-long barbican placed between an external double gate and a watchtower. Inside the fortress, a beautiful covered market (15C) which is still in use contrasts sharply with the martial austerity of the exterior.