The massive Main entrance of the Great Pyramid of Khufu .Most of the limestone blocks of the Great Pyramid weigh about 1.5 tons. The heaviest blocks in the Great Pyramid are the granite blocks used to roof the unloading Chambers estimated to weigh 80 tons.

Another view of The underground city of Derinkuyu is an archaeological wonder located in the Cappadocia region of Turkey. It is more than 85 meters below the surface of the Earth and consists of an eighteen-level tunnel system. A local found one of the entrances in 1963.

After more thorough investigation and some digging, a passage was discovered, which was later followed by about six hundred similar discoveries in other private houses.

Excavations began immediately and traces of an entire civilization were revealed below the surface, with residential houses, feed storage rooms, cattle stables, school, wine cellars and chapel.

The first few levels of the cave system were dug out by the Hettites, when the Frigians attacked them around 1200 BC, most of the city was probably built by the Frigians afterwards. The caves could originally be used for storing goods, but at the same time they provided a shelter from the current occupiers.

Each level of the city was carefully planned and divided according to specific goals. Each level is closed by a circular rock, which can only be moved from the inside, with a small, perfectly round hole carved in the middle, so that the intruders could be measured with a spear. They used clay pots as a toilets, lived next to torchlight, designated a place for dead bodies, and animals were kept in the areas closest to the surface to reduce the flow of odors and toxic gases, as well as to provide a living insulation layer for the cold months.

But the most impressive part of the building is the complex ventilation system and the protected well, which provided the whole city with fresh air and clean water. Thanks to more than fifty ventilation vents, air flowed naturally into residential houses and corridors, and the more than 55 meters deep well could be closed from underneath to prevent the enemy from access.

Derinkuyu’s exact function remains a topic of discussion. It is certain that its construction and use reflects a remarkable social and technical organizational level.

Discovering is like stepping back in time.

Walking through the corridors, the visitors can experience for themselves what life was like in an underground world, which is invisible to the naked eye, but very mysterious.

The secret will capture the imagination of future generations.