The Demir Baba Teke Mausoleum was probably erected between 1612 and 1617. Built over prehistoric and Thracian sanctuaries, the Teke is the grave of the spiritual leader of a community (probably Iranian) who preached fraternity and love of one's neighbour. The mausoleum comprises a six-sided building surmounted by a dome. Some of its walls are made of materials taken from previous edifices. For instance, on the eastern wall, you will see stones bearing low-relief carvings. The funeral chamber is decorated with mural paintings and inscriptions.