The Mysterious Wall with Sideways Keystone Cuts

In this chapter, they discuss the construction of a wall that shows evidence of reusing blocks from an older wall. The blocks are from the old Kingdom of Egypt and have Keystone cuts, but they have been placed sideways, rendering them ineffective. This suggests that the original wall with Keystone cuts was built during a time when megalithic instructions were being used prior to the old Kingdom of Egypt. They also mention a similar location in Vietnam called a chem.