One other thing. a straight line is easy to make with a beam of light. And a simple beam of light can be made from the reflection of a mirror. So it's not all the big a deal that the walls were straight.
This really piqued my interest a few years back...
http://www.crystalinks.com/ancientaircraft.html
Supposedly it was debunked as natural erosion of the original carvings...but still...it's eerie.
"One other thing. a straight line is easy to make with a beam of light. And a simple beam of light can be made from the reflection of a mirror. So it's not all the big a deal that the walls were straight."
My back yard wood deck, built by me (another amazing feat of civil engineering which will be studied for generations—or maybe not), I found a miraculous method for marking a straight line: tightly strung string! Yes, I do not mean to brag, but I was (am) centuries ahead of my time.