The age of the pyramids is remote and unknown, since Diodorus Siculus (tom. i l. i. c. 44, p. 72) is unable to decide whether they were constructed 1000, or 3400, years before the clxxxth Olympiad. Sir John Marsham's contracted scale of the Egyptian dynasties would fix them about 2000 years before Christ (Canon. Chronicus, p. 47).