Merzifonlu Kara Mustafa Pasha was a Grand Vezir to Mehmet IV, he lost his head after a second siege of Vienna in 1683, of which he had been in charge, failed to provide the conquest of the city. Apart from the Medrese there are other buildings, started in 1669 and finished by his son in 1690. It has a mosque that I could not visit, one of the few octagonal buildings to be used as a mosque. The complex, on Yeniçeriler Caddesi, is a cultural centre now, commemorating a famous poet Yahya Kemal, whose museum on the grounds I did not visit either.