My vote is for pyramids being some kind of energy device.
Pyramids (not only in Egypt but all over the world) have some interesting things in common.
- built at strategic ley lines on Earth also linked to certain stars (as above so below)
- similar sacred geometry mathematics
- built on top of some kind of underground moving water
- enormous stones made of energy conducting materials moved vast distances and precision cut - technology beyond that of ours today
- evidence they (original structures not the later rennovations) are much older than mainstream archeology wants to admit
etc...
I think they may have been used as "tombs" later on like the ufo turned into a shrine idea in this
scene from an Indiana Jones film. I don't think it was necessarily built by ETs but that our ancestors from prehistoric times had a different sort of consciousness that was able to access these things and writing wasn't needed back then because everybody was telepathic and able to read the akashic record.
just my 2 cents