Expeditions exploring deep, mysterious tunnels and caves in various parts of the world return with strange tales of subterranean civilizations, cities and advanced yet ancient technology.
Many of these remarkable underground worlds remain shrouded in mystery because we have not been able to locate them yet. There are also fascinating very old underground tunnels, caves and cities that have been discovered, but the history behind them remains unsolved because we have no idea who built them and for what purposes.

1. UNDERGROUND TUNNEL SYSTEM BENEATH THE PYRAMIDS OF GIZA

There is a lost history completely ignored by mainstream scholars when it comes to the Ancient Egyptian Civilization and the enigmatic Pyramids which according to many predates the Egyptian Civilization itself.
West of the middle pyramid on the Giza Plateau, the ground rises to its highest point where there are some of the surviving buildings of The Harvard camp, established by George Reisner in 1902 to pursue the aims of the Hearst Expedition of the University of California. The high ground suddenly drops away beyond the buildings leaving eroded cliffs facing north which have many tomb entrances dotted along its length.
The Labyrinth of Egypt has been described by a number of ancient writers such as Herodotus, Strabo, Diodorus, and Pliny. The labyrinth’s age and ancient origins are unclear, but at the time of Herodotus’ visit it was more than 1,300 years old

2. Tunnels in Bucegi Mountains

In the summer of 2003, in an unexplored area of the Bucegi mountains, an epochal discovery was found that would completely change the destiny of mankind.
There are 4 primary tunnels and further sub-tunnels that lead to deep underground places which you would have heard of.
In these tunnels you will find rooms, huge rooms, with huge tables and stone chairs for people much, much taller than us.
The projection room contains all our history and can be replayed visually.
A table where you can perform holographic experiments with DNA, mix and match anything you wish and see what the results would be.
These rooms were created at least 50,000 years ago and each is connected to each other, protected by an energy source which actives all as one is activated.

3. Underground City Beneath Death Valley

The very thought that there could be a secret city lying beneath California’s Death Valley that is more than 5,000 years old is astonishing and difficult for many people to believe. But for those who have entered the subterranean tunnels underneath the ground and visited this amazing location, it is all very real. There are many who believe that the underground city was once inhabited by an unknown race, now thousands of years later, the area is abandoned, however, visitors say that they have witnessed some strange artifacts while exploring inside.

The ancient city known as Shin-Au-Av could have been home to many different races, but it is important to look at the legends of the Paiute Indians before you start to imagine various creatures of the unknown lurking underground.

4. Lost Cave City in the Grand Canyon?

Did an ancient civilization live in caves below the Grand Canyon? This is as vague a statement as wondering why some of the ancient Mesoamerican people depicted their gods as white men or the Olmec gods looked African. Stretching the imagination … perhaps whatever was found in the Grand Canyon caves discussed below, is linked to Ancient Alien Theory. It is interesting to speculate on ancient Egyptians or Tibetans flying to the Grand Canyon in Vimanas, but, to date, there is no tangible proof to support these claims.

5. Highly Sophisticated Underground City Of Derinkuyu

The underground city of Derinkuyu is an ancient city located beneath the surface of the Derinkuyu district in the Nevşehir Province, Turkey. It is one of the most amazing underground cities to have been discovered, and no one knows its exact age, making this already awesome underground city even cooler.
In 1963, approximately 50 miles (30 km) south of Nevsehir, Cappadocia, Turkey, Omer Demir stumbled across a deep hole (in Turkish: derinkuyu) that led to a steep path leading deeper down to passages, niches and shafts dug into the bedrock.
After intensive excavation, it became clear that Derinkuyu was an entire city complex built in that hole beneath the surface