I recently heard that more man-hours went into landing a man on the
moon than any other single endeavour in human history-- in
particular, the great pyramid and the great wall of china were cited
as requiring far fewer man-hours than the apollo program.

If true, I find it very nice that a modern society could mobilize such
large resourcesfor such a huge undertaking. But is it true??

Has anyone else heard this claim? Can it really be true?