(2)
Prof. Michel Barsoum has found scientific evidence that parts of the Great Pyramids of Giza were built using an early form of concrete. Click here(1) to view a related graphic and photo.

1. http://archive.coasttocoastam.com/gen/page1823.html?theme=light
2. http://archive.coasttocoastam.com/gen/page1823.html?theme=light