The Alaettin Mosque is from 1221. It is in fact one very large room, that at some points widens, at others narrows. The pillars (or at least their capitals) have been taken from Roman buildings.

These are some buildings containing the graves (the buildings are called türbe) for sultans from the period.

The tomb on the right has never been finished, and therefore it is much lower than the one on the left. The latter, built in 1170, is the ‘Kılıç Arslan Türbesi’ (= Tomb of sultan Kılıç Arslan II, who reigned from 1156 to 1192).

Many Seljuk (and later Seljuk-style) mausolea are a stone evocation of the pre-islamic funeral hills of the nomads of Central Asia. During their lives, prominent clan members had their funeral hill (‘kurgan’) prepared; when death came, a circular tent was erected on top of the kurgan, and the deceased’s body was laid out, in order to be greeted a last time by the clan members. After this greeting period, the body was placed in the burial chamber inside the kurgan.
A ‘tent-style’ Seljuk Türbe has two parts: a circular or polygonal room with a pyramidal or cone roof, where a cenotaph sarcophagus can be visited and honoured; this is the part referring to the funeral tent. Beneath this ornamented construction the real burial chamber (‘cenazelik’ or ‘mumyalık’) is to be found, where the deceased’s remains were buried; this is the part referring to the burial hill.

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Agon Cultuur reisgidsen’ – M.Mehling, 1989 & Wikipedia.