Stonehenge
The mysteries surrounding circular Stonehenge, still seems to be Puzzling both historians and architects. What seems unanswered is why and how such big stones got transported here. It seems to be aligned with the rising and setting of the sun at the Solstices.
Was it some sort of circular festival place? New research as late as 3 weeks ago provide alternate theories that it was a burial ground.
Whatever be the reason, the ability to have transported such huge stones as far back as 3000 BC and 1600 BC is intriguing.