Petrie's Precision Survey of Giza

Sir William Matthew Flinders Petrie conducted the most accurate survey of the Giza pyramids to date, confirming extraordinary precision: the base is level to 2.1 cm, sides aligned to true north within 3/60th of a degree, and the perimeter-to-height ratio encodes pi. Petrie — a meticulous scientist — was so astonished by the precision that he initially could not explain how it was achieved. His measurements remain the gold standard 140 years later.