With the pyramids, maybe the ancient Egyptians were just really smart, or it could have been
a joint venture with an alien civilization.

The theory that the Great Pyramid was built in 20 years is also proven to be a complete fallacy, yet they still don't know how stones weighing many tonnes were moved into position. One relatively new theory is that they were 'levitated' using sound-waves and then manually guided into position. Maybe someone should bring one of the 'mummies' back to life and ask?