"The location of this entryway was forgotten in the following centuries, and when the Moslem caliph AI Mamoon attempted to enter the pyramid in 820 A.D., he employed an army of masons, blacksmiths and engineers to pierce the stones and tunnel his way into the pyramid's core. What prompted him was both a scientific quest and a lust for treasure; for he was apprised of ancient legends that the pyramid contained a secret chamber wherein celestial maps and terrestrial spheres, as well as "weapons which do not rust" and "glass which can be bent without breaking" were hidden away in past ages." --