The Cacabey Madrasa was commissioned by the governor Nureddin Cibril bin Caca Bey in 1272, under the reign of Seljuk Sultan Giyaseddin Keyhusrev III (Ghiyath al-Din Kaykhusraw III). Its architect is unknown. Built as a madrasa and used as an observatory, the building, which has undergone several renovations, now serves as a mosque.
The plan of the madrasa is a slightly distorted square, with two stories along its north side. Partially buried in the past, it remains slightly below the level of the street. The eleven-meter-tall portal on the north elevation leads through the entrance iwan, which is roofed by a barrel vault, to the central space. This space measures approximately eight meters per side and is topped by a dome with an oculus at its center. This dome is carried by four columns, two of which are embedded in the walls on the north side.
The main iwan to the south of the central space was used as the small mosque of the madrasa, and a smaller iwan to the east of the central space leads, with seven steps, into the tomb on the northeastern corner of the madrasa. This tomb, a rectangular space measuring approximately six meters on one side, is surmounted by a conical crown. West of the central space is an iwan-like space that functions as an entryway to the rooms on its three sides. A secondary space to the south of this "iwan" leads to a rectangular room at the southwestern corner of the madrasa. While the southern corner has a similar spatial configuration, the sizes of the spaces vary, due to the axial shifts in plan. There are two more rooms on the entrance floor, one of which is located on the east side of the entrance iwan, and the other on the northwestern corner of the madrasa. While the three cells and two rooms on the west have windows, the ones on the east are totally closed. The entrance iwan, which is shifted from the central axis, has an opening on its west side that leads to the upper floor. There is a narrow corridor here that leads into two rooms in the upper floor; these are the only two upper-story rooms, which run behind the north elevation.
The main configuration of the madrasa, as seen in its elevations, differs slightly from its contemporaries; the minaret, with its single balcony, is detached from the southwest corner of the madrasa, and the north elevation articulates the presence of the tomb and two small towers on the corner. Another tower is also found in the middle of the west elevation.
The portal to the madrasa is made of two layers of stone, light brown and yellow in color. Two decorated columns, raised on special bases, are located at the corners of the projecting portal. The madrasa's main inscription is found in the upper part of the portal niche, below the stalactites.
The madrasa is made of unornamented, cut stone, with the exception of the minaret, which is a brick structure on a stone base. Within, the mihrab is framed with stone and ornamented with five rows of stalactite carving above. The tomb area features mosaic tiles in black, white and in turquoise. Turquoise mosaics were also used in the minaret. The north elevation window into the tomb is adorned with stalactite carvings, and the lintel above it features an inscription that is a continuation of the one in the madrasa.
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