Dispatch from Stonehenge, Day 1

Under an overcast sky blanketing the Salisbury Plains in southern England, work began today on the most significant archaeological excavation in recent UK history: An attempt to unravel the mysteries locked within the sacred circle of Stonehenge. It is the first such exploration of the site in nearly 45 years.

Stonehenge is not only one of the world's most famous archaeological sites and an icon of English prehistory—it is also an enduring puzzle. Who made it, when was it constructed and, perhaps most crucially, why?

Theories abound. Some suggest that it served as calendar, aligning with the winter and summer solstices. Others regard it as a memorial to the dead.

Most archaeologists agree that Stonehenge was built in stages over the last 5,000 years. Initially, the site consisted of little more than a large circular ditch, surrounded by a bank of earth. This circular enclosure, or "henge," became a stone henge with the placement of a series of bluestones, which were originally arranged in two concentric circles. Only later did the builders introduce the larger—and more iconic—sarsen stones, to construct the imposing trilithons (two vertical stones capped by a horizontal stone lintel).

Although everyone knows what Stonehenge looks like, you have to visit the place to truly get a feel for its scale (the largest of the trilithons is nearly 24 feet tall). And while Stonehenge is impressive when viewed from the tourists' roped-off path circling the monument, the site takes on a new dimension when viewed from within the circle itself—something few visitors get to experience. Standing next to the sarsens for the first time today, and looking up at the lintels crowning the enormous trilithons, I began to get a deeper sense of why these structures have resonated so powerfully with visitors over the centuries.

The archaeological team will dig an 8-foot by 11-foot trench, about 3 feet deep, near one of the smaller bluestones. The dig, led by Professor Tim Darvill of Bournemouth University and Geoff Wainwright of the Society of Antiquaries, will last two weeks, and is intended to establish a precise date for when the bluestones were brought to the site. (Current estimates place the year at around 2,500 B.C.) The archaeological team also hopes to glean insights into how these stones were rearranged as Stonehenge was refashioned over the subsequent centuries.

The bluestones, which were quarried 155 miles away in the Preseli Hills of Pembrokeshire, Wales, are of particular importance to understanding Stonehenge. They were the first stones to be put in place, and could hold the secret as to why the ancient builders went to the trouble of lugging them all the way to Salisbury.

Darvill and Wainwright speculate that these stones were believed to have health-giving powers, and were brought to the Salisbury Plains to create a place of healing— a sort of prehistoric Lourdes. By using modern technology to pinpoint the age of these stones and the date of their arrival, the two scholars hope they will be able to confirm not only why but when the first stone monument was built.

As would be expected for such a momentous occasion, the beginning of the project was something of a media circus. The area to be excavated was marked out on Sunday afternoon, and blessed by a druid priest wearing an antler helmet. Then, this morning at 9:20 A.M., in front of an audience of news crews, Darvill and Wainwright dug out the first shovel loads of grass and mud, as they embarked on the apotheosis of their professional careers.

Small parties of reporters and photographers were then escorted into the circle of stones (not accessible in the standard tours of the site) to see the emerging trench firsthand, and to question the two professors— all under the watchful eyes of staff from English Heritage, the custodian of Stonehenge.

English Heritage has long been reluctant to allow excavations that could damage this precious monument. But Darvill and Wainwright's proposal, inspired by an imaginative theory and requiring relatively little disturbance to the site, was deemed acceptable. While the site needs to be preserved, English Heritage recognizes that it must also be studied further.

Meanwhile, the usual throng of tourists passed by on the path circling the monument. Anyone curious to know what all the fuss was about could witness events inside a specially erected marquee, which relayed live video feeds from within the stone circle—and sold a nice selection of Stonehenge T-shirts.

Dan Jones is a freelance science writer who has contributed articles to New Scientist.