Alaaddin Mosque is on the top of the so-called Alaaddin Mound (Alaattin
Tepesi). The Palace of the Seljukid sultans was once inside a citadel that
was standing on this small hill. The Alaaddin Mosque was built adjacent
to the palace following the example of Early Islamic palace mosques. The
mosque comprises two different structural units juxtaposed in different
periods. The east wing of the building is believed to have been built by
Sultan Mas'ud before 1155. There is a trapezoidal interior filled with
rows of Hellenistic and Byzantine columns, tied together by pointed arches
that run parallel to the mihrab wall. The west wing, on the other hand
is known to have been built during the first quarter of the thirteenth
century by the Sultans Izzeddin Keykavus and Alaaddin Keykubad. At the
centre of this wing, there is a domed bay in front of the mihrab. According
to Aptullah Kuran, this masjid was, in all probability, the private masjid
of the Seljukid royal palace, and it must have been combined with Mas'ud's
Old Mosque during the fourteenth century. There are two polygonal tombs
(kumbet) in the courtyard, which were built for the members of the Seljukid
dynasty.