Even with cranes, helicopters, tractors and trucks at our disposal, it would be tough to construct the Great Pyramid of Giza today. Its construction 4,500 years ago is so astounding in some people's eyes that they invoke mystical or even alien involvement. But the current theory of the building of the Great Pyramid — the notion that it was assembled from the inside out, via a spiraling internal ramp — is probably still the best construction plan.
Following that plan, we could replicate the Wonder of the Ancient World for a cool $5 billion.
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