Pyramids are structures with triangular surfaces that converge into a point. The base of a pyramid is typically three- or four-sided, but all pyramids have trilateral sides — isosceles or equilateral.

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For some people, the great pyramids of Egypt are a weird mystery. People still discuss how they might have been built, and why. But the Great Pyramid of Giza - built almost 4,000 years ago - for the ...