How did the pyramids stand without falling?

The individual stone blocks making them up are quite large and heavy; they're not going to be blown about by the wind.

Perhaps you've read something about the "angle of repose". However, this really only applies to small particulate matter; objects built of larger blocks can have a much steeper angle without falling over (for example, it's possible to make a perfectly vertical stack of bricks). There's no advanced miracle of engineering involved in the slope of the pyramids.