I really like the thought of the aliens having a connection to Egypt. I could base the theme on the theory of aliens visiting earth centuries ago and their printed clues to their existence on Egyptian art and hieroglyphs.
Mysterious Year-Old Pipework Discovered Under Chinese Pyramid Post In: Weird - By Ian Paxton - June 2015 Who could have built such a complex structure years ago, at a time when man had barely started using fire? The Baigong pipes.
The secret base at Groom Lake, Nevada also known as "Area or "Dreamland" has a massive Pyramid, but why? One can only speculate on its purpose but it is reasonable to assume its not just for decoration.