Open sesame - Earth.com

The thing confusing archaeologists was that Chankillo couldn’t have operated as a normal fort — if it was a fort at all. A glance at its three buildings revealed to the experts that they would be easily penetrable by invading forces. The solid construction evidently had some serious flaws. Photo Credit: Werner Forman/Universal Images Group/Getty Images

News coming your way
The biggest news about our planet delivered to you each day