Page "Great Pyramid of Giza" Paragraph 38

I. E. S. Edwards discusses Strabo's mention that the pyramid " a little way up one side has a stone that may be taken out, which being raised up there is a sloping passage to the foundations.

" Edwards suggested that the pyramid was entered by robbers after the end of the Old Kingdom and sealed and then reopened more than once until Strabo's door was added.

He adds " If this highly speculative surmise be correct, it is also necessary to assume either that the existence of the door was forgotten or that the entrance was again blocked with facing stones " in order to explain why al-Ma ' mun could not find the entrance.