This Hacı Kılıç Camii was built by vizier Ebu’l-Kasım bin Ali Tüsî, at the very end of the heydays of the Seljuk sultanate of Rûm. (In fact, their defeat at Kösedağ against the Ilkhanid Mongols happened 6 years earlier, in 1243). The building has two parts: adjacent to the mosque, to its south, stands a medrese/school. Originally the prayer room of the mosque opened directly into the open courtyard of the medrese; now these arches have been closed by glass windows. Both entrances (to the mosque’s prayer hall, and to the medrese) are placed in the eastern wall (the one shown on this picture).
The mosque got its actual name in the 16th century, due to a restoration that turned the medrese into a zaviye (dervish house). Hacı Kılıç was a prominent şeyh (= leader) of that dervish Order.
The slender minaret is much younger than the rest (not dated, but probably 19th century).