Stonehenge builders used Pythagoras' theorem 2,000 years before Greek philosopher was born, say experts The builders of Britain’s ancient stone circles like Stonehenge were using Pythagoras' theorem 2,000 years before the Greek philosopher was born, experts have claimed. A new book, Megalith, has re-examined the ancient geometry of Neolithic monuments and concluded they were constructed by sophisticated astronomers who understood lengthy lunar, solar and eclipse cycles and built huge stone calendars using complex geometry One contributor, megalithic expert Robin Heath has even proposed that there exists a great Pythagorean triangle in the British landscape linking Stonehenge, the site from which...