The Karatay Madrasa, on the northeast slope of Alaeddin Hill, is one of the great surviving works of Seljuk architecture. It was built in 1251 by Celaleddin Karatay, the vizier of Sultan Izzedin Keykavus II, as a school for the study of Islamic theology and law. The marble entrance portal is the showpiece on the outside — a complex of geometric patterns and Arabic calligraphy in low relief, dark stone framing the recessed doorway in muqarnas vaulting.
Inside, the central hall is roofed by a domed ceiling covered entirely in Iznik-style tiles, an early-fourteenth-century scheme of star patterns in dark turquoise and indigo with calligraphic friezes around the rim. The pool beneath, reflecting the dome, multiplies the effect. The surrounding rooms now display a substantial collection of Seljuk and Ottoman tilework — the Karatay Tile Works Museum — including some of the earliest figurative Seljuk tiles, with images of sphinxes, double-headed eagles, and human figures, in styles owing more to Persia and Central Asia than to the strictly aniconic Ottoman tradition.
Allow at least an hour, more if you want to study the inscriptions on the entrance portal. The museum is closed Mondays.