It is a mystery that has slot confounded experts for centuries - how were huge stones transported 180 miles (290km) from the Preseli Hills to Stonehenge?
Some think humans, or even cows, pulled them to their resting place on Salisbury Plain.
However, a Denbighshire man believes it was a long-forgotten "machine" which appeared to defy gravity and was even possibly referenced in the Bible.
A leading expert said his theory was "as good as any, and better than most".
"It may look like something out of Last of the Summer Wine, but we've lifted a third of a tonne with it and theoretically it could move any weight," said carpet fitter Steven Tasker, 66, from Llanrhaeadr.
A lover of Ancient Egypt, Steven wanted to explain how the Pyramids were built - but believes his theory also sheds light on how stone circles were created on various sites, from Orkney's Skara Brae to Stonehenge.
It was on a trip to Cairo in 2004 that he started to consider whether some ancient artefacts were not what they appeared to be.
For example, what looked like eye make-up jars could have been stone rollers to help move objects.
There were also "rockers" assumed to be sleds for pulling items - however, Steven believes they could also be part of this complex machine.