Maybe it was discussed before in dozens thread about pyramids but I failed to found it.
Anyway,as I understood pyramids in Giza are align to true north.
I didnt found any logical idea.
Question hit me when I was reading this article
The tombs are aligned north-south with an accuracy of up to 0.05 degrees. How the Egyptians did this has been unclear. Today, you could align a building north-south by pointing the sides towards the pole star, which sits roughly at true north. However, a wobble in the Earth's axis of rotation (called precession), means that the positions of the stars changes gradually over time.In the third millennium BC, no star sat at the north pole.
Edited by Melo, 29 April 2012 - 07:18 PM.