Among the most important surviving Seljuk mosques in Turkey, the Ulu Cami (1273) is supported by 40 fat, soaring wooden columns with intricate stalactite capitals and features a flat-beamed roof. Outside, local green tiles decorate the minaret.
The mosque should be open for visiting daily between 10am and 6pm (excluding prayer times), but occasionally it's locked. To make sure you can gain access, arrive just after prayers have finished. It's located right under the castle in the old town.