There's a growing body of evidence to suggest that dinosaurs built the Pyramids.
back at the dinosaur time it was easy to lift heavy stones, so not that difficult to build pyramids.
"Dinosaurs and the Expanding Earth was first published it proposed a startling idea to explain the long-standing puzzle of the dinosaurs' gigantic size. Stephen Hurrell presented scientific evidence that dinosaurs lived in a reduced gravity and this allowed them to grow to gigantic proportions. The Reduced Gravity Earth theory explains why all land-based life has shifted towards a larger scale on the ancient Earth. This includes gigantic dinosaurs, plants and insects."
the expanding earth theory was actively discussed in Nature etc.
"Paul Dirac suggested in 1938 that the universal gravitational constant had decreased in the billions of years of its existence. This led German physicist Pascual Jordan to a modification of general relativity and to propose in 1964 that all planets slowly expand. "