Iznik was the centre for the production of high grade frit ware. The best specimens are in several of the major museums of the world, many are in the Çinili Kösk on the ground of the Archaeology Museum in Istanbul. Or they are on the walls of the mosques built during the heyday of Ottoman reign, the mid-sixteenth century. The best in Istanbul are Sokollu Mehmet mosque and Rüstem Pasha Mosque, and in Edirne the Selimiye mosque. The Süleymaniye in Istanbul again is quite good also. The best book I know is Iznik, The pottery of Ottoman Turkey by Nurhan Atasoy and Julian Raby. You will find it in the better books shops in Istanbul, some museums and abroad. It costs an arm and a leg, but gives illustrations and in-depth treatment on almost any aspect of this great art.
I here present some of the better pieces from the museum in Iznik, often broken, from the early stages of production or produce for the ordinary people, who could not afford the masterpieces.