This is the Burmalı Minare Camii (Spiral Minaret Mosque), built between 1237-1247 by the Selcuks.

The octagonal structure on the left of the main entrance is a türbe (mausoleum), erected for Ferruh Bey and his son Yusuf Bey, two state officials during the reign of sultan Giyasettin Keyhüsrev II (1237-1247). This is attested by the building inscription on the tomb; since no such inscription could be found for the mosque, these dates are also applied to it, although the house of prayer could be older.

The mosque was severely damaged in 1590 (by earthquake) and in 1602 (by fire), but rebuilt before 1640, when the Turkish writer/traveller Evliya Çelebi saw and described it.
Photographs from the 1980’s show the mosque and its interior in a sorry state, with grass and bushes on its roof and piles of rubbish inside. It has been cleaned up and repaired since, and is now open again to worshippers.

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Vakıf Abideler ve eski Eserler’ - Vakıflar Genel Müdürlüğü, Ankara 1983.