This is the Medrese part of the Green Mosque complex, housing the ethography and islamic art museum. There is some fine decoration on the outside and a decent garden to give you something to see in case the museum is closed.

On the picture: The tile work decoration above the entrance door, which lies in an iwan-like vestibule facing the north (i.e. outward).

An iwan (Persian & Turkish: ‘eyvān’) is a rectangular hall or space, usually vaulted, walled on three sides, with one end entirely open. This architectural form can be used for entrances, but also (as it is the case here) to create half open rooms looking out at a central yard. The iwan as used in Anatolian Seljuk ‘medrese’ and later in early-Ottoman ‘Bursa-type’ mosques was imported from Islamic Persia, but was invented much earlier and fully developed in Mesopotamia.

Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Vakıf Abideler ve eski Eserler III’ - Vakıflar Genel Müdürlüğü, Ankara 1983
& Several personal visits to the Yeşil Medresesi (between 1979 and 2002).