

The Derinkuyu underground city is a vast, multi-level subterranean complex located in the Cappadocia region of Turkey. It is believed to have been built during the Byzantine era, between the 7th and 13th centuries AD, and was used as a shelter by early Christians fleeing persecution. However, there is an alternative theory about the construction and use of the underground city that suggests it may have been built earlier and for different purposes.
One theory is based on the fact that the underground city is located in an area that was affected by the last ice age, which occurred around 12,000 years ago. During this time, the region was covered in glaciers, and it is believed that the underground city was built as a means of survival for the ancient humans who lived there. According to this theory, the underground city was created as a shelter from the harsh weather conditions and as a means of protection from wild animals.
According to another theory, the Derinkuyu underground city may have been built by the Hittites, an ancient Anatolian people, as early as the 2nd millennium BC. The Hittites were known for their advanced engineering and architectural skills, and the underground city bears similarities to other Hittite structures. Proponents of this theory also point to the fact that the underground city is located in an area that was within the Hittite empire, and that the Hittites had a need for underground structures due to the frequent earthquakes in the region.
This alternative theory also suggests that the underground city may have been used for different purposes than as a shelter for early Christians. The Hittites were known to have used underground structures as granaries, storage facilities, and even as palaces. It is possible that the Derinkuyu underground city served similar purposes for the Hittites.
The city is composed of a series of interconnected tunnels and caverns that extend to a depth of approximately 60 meters (197 feet). It is estimated that the city could have housed up to 20,000 people at its peak. The complex is divided into several levels, each with its own living quarters, storage rooms, stables, and communal areas. There are also ventilation shafts and wells to provide fresh air and water.
One of the most striking features of the Derinkuyu underground city is the intricate system of doorways and passageways that were used to control access to different areas of the city. Many of the doorways are narrow and low, making it difficult for intruders to enter. Additionally, many of the doors are designed to be able to be closed from the inside, allowing residents to seal off certain areas of the city in case of attack.
The living quarters within the city are quite small and cramped, but they were designed to be functional and efficient. Many of the rooms have stone or mud-brick walls and floors, and are lit by small openings in the ceiling that let in light from the surface. Despite the cramped conditions, the city was quite advanced for its time, with features such as running water and drainage systems.
The underground city also contains communal areas such as meeting rooms, chapels, and cemeteries. The chapels within the city are particularly interesting, as they provide a glimpse into the religious beliefs of the early Christians who lived there. Many of the chapels are adorned with frescoes and other religious artwork, and some contain underground baptismal pools.

The Derinkuyu underground city was discovered in the early 20th century and was opened to the public as a tourist attraction in the 1960s. Today, visitors can explore the various levels of the city, including the living quarters, communal areas, and ventilation shafts. Some areas, however, are closed off to the public for preservation reasons.
The underground city of Derinkuyu is a fascinating and unique historical site that provides insight into the lives of early Christians who lived in the region during a time of persecution. It is a testament to the ingenuity and resourcefulness of the people who built and lived in this underground complex. The Derinkuyu underground city is a must-see destination for anyone interested in history, architecture, and human ingenuity.