ve joints).The 35-ton heel stone was possibly placed during the second period. Its placement was one of the most sophisticated accomplishments of that age and provides the best evidence that early people used astronomy. On Midsummer Day (June 24 then, now June 21) a person standing in the center of the circle can see the sun rise directly above the heel stonePERIOD III (c. 2000 - 1550 BCE)A circle of 30 sarsen-stone (weighing up to 50 tons each) uprights 30.5 m (100 ft) in diameter and capped by a continuous ring of sarsen lintels was erected in the center of the site. This circle surrounds a horseshoe-shaped setting of five sarsen trilithons (formations in which two uprights support a lintel). After transporting the sarsen stones from Marlborough Downs, 30 km (20 mi), the stones were shaped and jointed together with stone hammers. Other changes involved adding, moving, and rearranging stones that had been used during the second period. No other megalithic structure in northwestern Europe displays the precision and architectural refinement that Stonehenge does. Some of the bluestones were later reerected in the center in an oval structure that contained at least two miniature trilithons, and holes were dug for the rest to be set in two concentric circles (the so-called Y and Z holes) outside the sarsen circle. This plan was abandoned unfinished, however, and the bluestones were finally rearranged (c.1550 BC) in the circle and horseshoe whose remains survive today.PERIOD IV (c. 1550 - 1100 BCE)The Avenue was extended to the River Avon, 2 km (1.25 mi) from StonehengeLEGENDS1.The legend of King Arthur provides another story of the construction of Stonehenge. It is told by the twelfth century writer, Geoffrey of Monmouth, in his History of the Kings of Britain that Merlin brought the stones to the Salisbury Plain from Ireland. Sometime in the fifth century, there had been a massacre of 300 British noblemen by the treacherous Saxon leader, H...
