Stonehenge: Summary of Archaeological Findings at the Megalithic Monument

Megalithic Monument on the Salisbury Plain of England

Stonehenge in sepia, England
Stonehenge in sepia, England. Sarah Casha

Stonehenge, quite possibly the most famous archaeological site in the world, is a megalithic monument of 150 enormous stones set in a purposeful circular pattern, located on the Salisbury Plain of southern England, the main portion of it built about 2000 BC. The outside circle of Stonehenge includes 17 enormous upright trimmed stones of hard sandstone called sarsen; some paired with a lintel over the top. This circle is about 30 meters (100 feet) in diameter, and, stands about 5 meters (16 feet) tall.

Inside the circle are five more paired-and-linteled stones of sarsen, called trilithons, each of these weighing 50-60 tons and the tallest 7 meters (23 feet) high. Inside that, a few smaller stones of bluestone, quarried 200 kilometers away in the Preseli Mountains of western Wales, are set in two horseshoe patterns. Finally, one large block of Welsh sandstone marks the center of the monument.

Dated Phases at Stonehenge 

Dating Stonehenge is tricky: radiocarbon dating has to be on organic materials and, since the monument is primarily of stone, the dates must be in close association with construction events. Bronk Ramsey and Bayliss (2000) summarized the available dates in this manner. 

  • Mesolithic: radiocarbon dates range between 6590-8820 cal BC, a ring of posts? unclear on the extent of use
  • Phase 1 3510-2910 cal BC: construction and initial use of the first monument, including a segmented ditch with a bank and counterscarp bank and a ring of posts. At the base of the ditch were found over 100 antlers and animal bones. Radiocarbon dates on the animal bone
  • Phase 2 3300-2140 cal BC: elaborate timber settings built in the center and across the eastern side of the monument, the ditch silted up and cremation burials were placed in and around the monument. Radiocarbon on animal bone and antler
  • Phase 3 2655-1520 cal BC: the first stone monument built, echoing the pattern of the timber circle. Radiocarbon on antlers: Sarsen circle: 2620-2480 cal BC; Beaker Age burial: 2360-2190 cal BC; Sarsen trilithons 2440-2100 cal B; Bluestone Circle 2280-2030 cal BC
  • Phase 4 2580-1890 cal BC: the avenue constructed, parallel ditches which extend for 2.8 km from the monument to the river Avon


Stonehenge has been the focus of archaeological investigations for a very long time indeed, beginning with the likes of William Harvey and John Aubrey in the 17th century. Although claims for Stonehenge's 'computer' have been pretty wild, the alignment of the stones is widely accepted as intended to mark the summer solstice. Because of that, and because of a legend that associates Stonehenge with the first century AD druids, a festival is held at the site every year on the June solstice.

Because of its location near two major British arteries, the site has also been subject to development issues since the 1970s.


See Solstices at Stonehenge for photos and ancient observatories for others.

Baxter, Ian and Christopher Chippendale 2003 Stonehenge: The brownfield approach. Current Archaeology 18:394-97.

Bewley, R. H., S. P. Crutchley, and C. A. Shell 2005 New light on an ancient landscape: Lidar survey in the Stonehenge World Heritage Site. Antiquity 79:636-647.

Chippindale, Christopher 1994 Stonehenge Complete. New York: Thames and Hudson.

Johnson, Anthony. 2008. Solving Stonehenge. Thames and Hudson: Lond.

Bronk Ramsey C, and Bayliss A. 2000. Dating Stonehenge. In: Lockyear K, Sly TJT, and Mihailescu-Bîrliba V, editors. Computer Applications and Quantitative Methods in Archaeology 1996. Oxford: Archaeopress.