I like a good conspiracy to get stuck into but this one doesn't really sit right with me. Wouldn't you think that the aliens would have built something a little more... high tech? Judging by their swish blinking flying saucers it's permissible to think that maybe the pyramids should have been built out of metal and glass instead of dusty stone. With a few escalators and automatic doors? A few LED lights inside would be quite nice too. Even in 2500BC the aliens would be lightyears ahead of us in terms of technology and design.
Instead of this:
You'd think they would built something like this: