The Cappadocia region of Turkey is home to astonishing underground cities. These cities, formed from volcanic lava, date back to the early days of Christianity. Although the original inhabitants were not the builders, they developed a vast underground network over time. The underground cities feature not only complex transportation systems but also living facilities such as kitchens and ventilation shafts. There is much speculation about the identity of the builders and the purpose of these cities, but it is widely believed that they were constructed to evade attacks from flying enemies. The existence of these underground cities remains an unsolved mystery to this day.