This is one of the oldest human-made structures ever discovered. It is around 12,000 years old! Despite its importance, we know virtually nothing about the site, the people who built it, or the purpose it served. Many think Gobekli Tepe may have been a temple of some sort.
It consists of numerous megaliths, with multiple stone circles containing over 200 large stone pillars (up to 20 feet high), many with detailed carving of animals on them. It is thought that their job is to protect the deceased, though no graves have ever been found at the site.
There are also stone rooms of more than one level, which is an amazing innovation for the era. It is also a complete mystery how all this could have been done, the largest carved block used at the site weighs over 50 tons and the main complex is nearly 1,000 feet long.