"It is believed that these underground cities were enlarged during early Christians times to provide refuge from invaders and persecutors. One of the largest of about forty such cities, called Derinkuyu, was found accidentally in 1963...Derinkuyu is believed to have held up to twenty thousand people and could be as many as eighteen to twenty stories deep. Much of this underground city has not been explored due to cave-ins. " -http://www.rdricketts.com/uncity.html
Derinkuyu (which means "Deep Well") had a wine press, places for livestock, places to bury the dead, a chapel and even a school. It's all carved out of hardened lava as is the city of Goreme.
The "confessional" (with my tour guide in the middle). Go through the entrance on the left and come out on the right. Do this 3 times and your sins were forgiven.
"Open Air Museum" where Christians used to live and had their chapels. This community is all carved out of hardened lava.
The little holes are where they kept the pigeons so that they could collect their poop and use it as fertilizer. This is why Cappadocia is known for it's wine: pigeon poop.