More time had past between the building of the pyramids to Cleopatra's time, than has past from her time to ours.

We are talking truly ancient people. It's hard sometimes to wrap our heads around the fact that they were essentially the same as modern humans. Maybe shorter in height and lifespan, but the same intelligence capacity. That could be said for humans going back 100k years or more, way before written history. They were smart, just severely limited in what they knew about the world.

Besides, we couldn’t build something like the pyramids today. The software and legal costs would be too high.

Not so sure their business management skills were so much better. Have you noticed the skylines and scale of modern cities? And it didn't take modern man generations to build the Luxor in Las Vegas. But yes, it is extremely impressive what the ancients did without modern technology. I suppose you can get a lot done with enough slaves, guards and religious fanatics determined to carry out multi-generational projects. Throw in a few decent mathematicians and architects, and presto.