They're in Egypt, the builders would have been "Ancient Egyptians" regardless of whether that means dynastic Ancient Egyptians or a pre-dynastic "lost civilization". That being said there are a lot of interesting unanswered questions, e.g. why are pyramids newer than the Giza complex less-sophisticated? The fact that we don't know how they are built tells you all of these are still questions completely unanswered by archeology.
Why is New York Penn Station so ugly and drab compared to Grand Central even though it’s newer? Even the style of decoration is entirely different and much richer on the older and larger building.
Could it simply be a question of society’s priorities and resourcing? Nah. After all the Americans were a fairly primitive culture primarily known for hamburgers and baseball. Most likely Grand Central was built by aliens or an older Native American culture.
Indeed. For some reason this obvious conclusion doesn't satisfy the pyramid theorists, even though ancient Egypt's many periods of cultural decline and later resurgence are well documented.
the economic case is more compelling in this example. grand central is still largely the same structure that was built in 1910 at the peak of rail's dominance. penn station was demolished and rebuilt to sell air rights during a sharp decline of intercity rail ridership.
I guess demolishing an iconic building could itself be evidence for cultural decline, but stuff like TWA flight center was being built at the same time. the dollars followed the passengers.
Were there less laborers available after the Giza pyramids? Of course s/laborers/slaves/ would be implied. If the labor force was smaller later, would that contribute to less-sophisticated?
