Afyonkarahisar is a Central Anatolian city with a name that means "opium black fortress", and the fortress still explains the place at a glance. A dark volcanic crag rises straight above the old centre, with the castle walls on top and mosques, lanes, and markets gathered below.
The city is not polished, but it has real substance. The climb to Afyonkarahisar Castle gives you the view, while Ulu Camii is one of Anatolia's great timber-roofed Seljuk mosques. Around the lower slopes are smaller Ottoman and Mevlevi sites that make the old town worth a slow walk.
Afyon is also known for marble, poppies, mineral water, and thermal hotels on the roads around town. It works well as a stop between Ankara, Konya, Izmir, and the Aegean, but the castle and mosque give it enough character for a day of its own.