The pyramids were built extremely accurately, aligned with the cardinal directions, and squared and levelled as well.

The most impressive aspect, however, is their positioning by the 30th degree of latitude.

Whilst algning the early pyramid with NSEW, using the circumpolar stars, they noticed that the altitude of the pole changed with movement NS. To celebrate this revelation they built their greatest monumental project on the nearby 30th degree latitude with an incredibel accuracy, 29.98 degrees.

These monumental structures are now known as the Great Pyramids of Giza.

This site will give you alot of detail into the construction of the pyramid's
Go to: http://www.touregypt.net
Scroll down to master index and it will take you to Building materials of the pyramid Builders, and
Construction of the pyramids, Part I, Orientation and Layout of the Pyramid platform.
Interesting reading!