A famous megalithic structure, the focus of a cluster of ceremonial sites on Salisbury Plain in Wiltshire (England). Scientific study and excavation over many years have revealed a complex history with three main phases of modification (c. 3000-1600 BC) contributing to the Stonehenge seen today. Sarsens and bluestones, the latter probably brought from South Wales, are set upright in concentric circles and horseshoes the orientation of which suggests one purpose as being sun and moon observation. The alleged "Druid" connection is entirely spurious, dating only from the 18th century  ad.