155: Pre-Medieval Math, Pyramids part two

Here are the pyramids at Giza, viewed from a satellite. Notice that they are aligned to the north-south lines ... in fact, to within a 0.05 degree. Also measurements of the plateau they sit on have determined that the foundation was carved into the bedrock and the entire site was leveled to within a fraction of an inch.

It's known how the Egyptians managed to perform this feat with the simple tools they had ready and now it's time for you to consider it and try to figure it out..

String, standard measuring sticks carved from granite, a good pair of eyes, that's all. Remember, they were just as smart as you and you are just as smart as they.

1. How did they align the edge N-S?
2. How did they level the base so precisely? 

Give up? Look at the alt text of the photo.

Was it aliens?

No, that's just crazy talk.

Look at the alt text for the pyramid photo for the explanation.

Here's another ..