The startling 1960s theory that Stonehenge was a prehistoric computer

In 1966 Boston astronomer Gerald Hawkins argued that Stonehenge functioned as a prehistoric computer for tracking the Moon and forecasting eclipses, citing 56 holes in the outer circle that match a lunar counting pattern. Using an early IBM computer at Harvard-Smithsonian Observatory, he modeled sightlines and published the theory in his 1965 book *Stonehenge Decoded*, which dominated scholarly debate for decades.