English: The Ulu Cami (Great Mosque) of Kayseri. Detail of the minaret.

Here's a description of the building according to the Grove Encyclopedia of Islamic Art and Architecture (2009, see entry for "Kayseri"):

"The congregational mosque (Turk. ulu cami) was founded in 1135 by the Danishmend Malik Muhammad as a basilican structure with a dome in the bay in front of the mihrab and a small open dome in the center, but the irregularity of the plan and the diversity of the materials used attest to repeated repairs and restorations over the centuries. An inscription on the north wall states that the building was restored by Muzaffar al-Din Mahmud ibn Yaghıbasan in 1205–6 during the reign of the Saljuq sultan Kaykhusraw I. On the west, an octagonal plinth supports a thick cylindrical minaret of brick dating from the Saljuq period."