Why and how does the pyramid still exists?

The only structure of the 7 Ancient wonders still in existence today, the Pyramids of Egypt are a tribute to the prowess of their builders and architects. They still exist today because, the shape of a pyramid is such, that there is no way an invading force can topple it, and no earthquake could shake it from its foundations. Although the weather has taken its toll on the outer layer of the pyramids, it would take many thousands of years to completely wear them away.