There are dozens of underground cities sprinkled all around the Anatolian area, with labyrinthine hallways and 5-6 levels of floors and rooms, most of them not fully excavated yet. Ingeniously created to allow inhabitants to escape the blisteringly hot summers, acquire and store water, etc. They were also created with defense in mind - the narrow hallways allowed only one outside attacker at a time to proceed through them, and the curves in the halls made bows/arrows and spears essentially useless.