Explanation

The Tibetan Plateau (Pamir Plateau) is known as the Roof of the World.

It's also the thickest crust in the world, between 70 and 90 kilometers.

The plateau is the world's largest and highest.

Its average elevation is more than 4,500 meters (14,764 feet).

Additional information 

The Shandur Pass in Pakistan is also sometimes called "the roof of the world".