Derinkuyu Underground city is a wonderfull and unbelieve place for me because as we know,in Byzantine Age,their tecnology wasn't today's but they digged 40 metres and they built an underground city under 40 meters.in normally as we know,Although only ants can do such this building,People did it at that time with just pickaxe and oar.it shows that,people can do everything.but ı suggest you to visit Derinkuyu underground city.
