Stonehenge is one of the oldest mysteries known to man, up there with the Great Pyramids of Giza on the list of inexplicable feats of astronomy and engineering by the ancient world. And while archaeologists have spent decades trying to uncover the origin of the massive stones that make up the Stonehenge structure, it took the kind gesture of a 90-year-old restoration worker to finally crack the case.

With the first henge being built roughly 5000 years ago, Stonehenge is one of the oldest archaeological sites in human history. Dating back 500-1000 years longer than the Great Pyramids of Giza, it has puzzled archaeologists for generations.

Photo by David Goddard/British Geographical