A recently published analysis draws attention to the fact that the stones display mirrored symmetry and that the only undisputed alignment to be found is that of the solstices, which can be regarded as the axis of that symmetry. This interpretation sees the monument as having been designed off-site, largely prefabricated and set out to conform to survey markers set out to an exact geometric plan.

The idea of ‘precision’ (below) demands that exact points of reference were used, both between the structural elements and in relation to the axis (i.e. that of the solstices). Johnson’s asserts that prehistoric survey markers could not have been placed within the footprint of the stones, but must have been (as in any construction) external to the stones. That almost all the stones have one ‘better’ i.e. flatter face, and that face is almost invariably inwards, suggests that the construction was set out so that the prehistoric builders could use the center point of the inner faces as reference. This is very significant in respect of the Great Trilithon; the surviving upright has its flatter face outwards (see image on right), towards the midwinter sunset, and was raised from the inside. The remainder of the trilithon array (and almost all of the stones of the Sarsen Circle) had construction ramps which sloped inwards, and were therefore set up from the outside. Placing the centre face of the stones (regardless of their thickness) against markers would mean that the ‘gaps’ between the stones were simply consequential. The study of the geometric layout of the monument shows that such methods were used and that there is a clear argument for regarding other outlying elements as part of a geometric scheme (e.g. the ‘Station Stones’ and the stoneholes 92 and 94 which mark two opposing facets of an octagon). A geometric design is scalable from concept to construction, removing much of the need for measurements to be made at all.

Much speculation has surrounded the engineering feats required to build Stonehenge. Assuming the bluestones were brought from Wales by hand, and not transported by glaciers as Aubrey Burl has claimed, various methods of moving them relying only on timber and rope have been suggested. In a 2001 exercise in experimental archaeology, an attempt was made to transport a large stone along a land and sea route from Wales to Stonehenge. Volunteers pulled it for some miles (with great difficulty) on a wooden sledge over land, using modern roads and low-friction netting to assist sliding, but it became clear that it would have been incredibly difficult for even the most organized of tribal groups to have pulled large numbers of stones across the densely wooded, rough and boggy terrain of West wales.

Josh Bernstein and Julian Richards organized an experiment to pull a 2 ton stone on wooden tracks with a group of about 16 men. They placed the stone on a wooden sledge then placed the sledge on a wooden track. They pulled this with two gangs of about 8 men. To move the stones as many miles across Southern england, the creators of Stonehenge would’ve had to build a lot of track, or move and rebuild track in pieces, as the stones migrated to their final destination.

A recent article has argued that the massive stones could be moved by submerging in water and being towed below an ancient vessel or group of vessels. This technique would have two significant advantages. It would reduce the load born by the vessel while part of the stone’s weight is displaced by the water. Secondly, the arrangement of the load below the vessel would be much more stable and reduce the risk of catastrophic failure. Naturally, this would apply only for transportation over water. The technique was tried during the Millennium Stone Project 2000, with a single bluestone slung beneath two large curraghs. The sling frayed away, and the stone plunged to the bed of Milford Haven.

It has been suggested that timber A-frames were erected to raise the stones, and that teams of people then hauled them upright using ropes. The topmost stones may have been raised up incrementally on timber platforms and slid into place or pushed up ramps. The carpentry-type joints used on the stones imply a people well skilled in woodworking and they could easily have had the knowledge to erect the monument using such methods. In 2003 retired construction worker Wally Wallington demonstrated ingenious techniques based on fundamental principles of levers, fulcrums and counterweights to show that a single man can rotate, walk, lift and tip a ten-ton cast-concrete monolith into an upright position. He is progressing with his plan to construct a simulated Stonehenge comprising of eight uprights and two lintels.

Alexander Thom was of the opinion that the site was laid out with the necessary precision using his megalithic yard.

The engraved weapons on the sarsens are unique in megalithic art in the British Isles, where more abstract designs were invariably favoured Similarly, the horseshoe arrangements of stones are unusual in a culture that otherwise arranged stones in circles. The axe motif is, however, common to the peoples of Brittany at the time, and it has been suggested at least two stages of Stonehenge were built under continental influence. This would go some way towards explaining the monument’s atypical design, but overall, Stonehenge is still inexplicably unusual in the context of any prehistoric European culture.

Estimates of the manpower needed to build Stonehenge put the total effort involved at millions of hours of work. Stonehenge 1 probably needed around 11,000 man-hours (or 460 man-days) of work, Stonehenge 2 around 360,000 (15,000 man-days or 41 years). The various parts of Stonehenge 3 may have involved up to 1.75 million hours (73 000 days or 200 years) of work. The working of the stones is estimated to have required around 20 million hours (830 000 days or 2300 years) of work using the primitive tools available at the time.[citation needed] Certainly, the will to produce such a site must have been strong, and it is considered that advanced social organization would have been necessary to build and maintain it. However, Wally Wallington’s work suggests that Stonehenge’s construction may have required fewer man-hours than previously estimated.

Tags: Construction, design