There is evidence for Stonehenge being a place of congress dating back 10,000 years, but the main enclosure (originally comprising a circular bank of chalk surrounded by a ditch, with two entrance points) dates to around 3000 BCE. Over the next few hundred years, concentric rings, first of timber and later of stone, were added internally: the site was clearly used for burials at this stage. The main construction of the iconic stone monument took place c. 2600–2400 BCE; first the 30 massive sarsen stones of the outer ring, then the capped arch trilithons of the inner horseshoe. Future phases of activity included the repositioning of some of the central stones and the erection of four Station Stones on mounds around the boundary. The axis from the centre, through the heelstone and the Avenue, aligns with the setting sun of the winter solstice, suggestive of the site’s ritual and religious significance.