History & Engineering: How Stonehenge Was Built.

The huge stone on the ground was 20 ft long and weighed 50 tons. At its foot lay a pit 8 ft deep, three sides help up by wooden stakes and the fourth- nearest to the base of the stone- shaped as a ramp. A team of men had excavated the pit using deer antlers as picks and ox shoulder blades as shovels. Ropes of animal hide and plant fibre were lashed around the stone ready to haul it upright.

Ropes, pits and mountain of timber

In 2000BC Salisbury Plain, in the west of England, was the scene of backbreaking toil as the largest megalithic stones were erected at Stonehenge. Raising the head of a monster stone the first few feet off the ground was the hardest task, even with the help of shear legs- lifting tackle hung from two spars joined at the top and spread at the base. As the head of the stone rose, men stacked timber beneath it to stop it falling back again. The pulling became slightly easier as the angle increased, until the foot of the stone began to slip down the sloping side of the pit. The men levered the stone with long wooden poles, using the timber underneath as a fulcrum. Finally the base of the stone hit the bottom of the pit. Stakes along the pit's edge stopped the stone toppling towards.

Magic Touch

In the Middle Ages, scholars thought that Stonehenge was built by the 5th century British king Vortigern and his wizard, Merlin. A 14th century illustrator shows Merlin directing the work.

The building of Stonehenge took place in three phases over 1600 years. The first began 3100BC, more than 500 years before the Egyptians started work on the Great Pyramid. These Stone Age builders built a circle 380 ft across, formed by a low outer bank surrounding a ditch, with another bank about 6 ft high inside the ditch. At the start of the third phase, around 2100BC, a double circle of 80 large bluish stones, known as bluestones, was added. These were dragged by men and oxen and floated on rafts from quarries 130 miles or 210 km away in the Preseli Mountains of southwest Wales.

Shaping
Using a rock as a hammer, a workman gives a smooth finish to one of the stones. As they were meant to be seen from within, the stones' inner faces and sides had a smoother finish.

Positioning
The builders ease the lintel into place after raising it from the ground on a laboriously hand-built deck of logs. Holes on the side and bottom face of each lintel match projections on its neighbour and on the stone below. The stones are surrounded by three rings of holes, or pits, some of which were used for cremation burials.

Between 2000 and 1550BC, early Bronze Age people removed the bluestones and erected a ring of 30 sandstone uprights, 16 ft tall, linked at the top by horizontal lintels, each weighing 7 tons. Inside the ring they set five even taller 'triliths', grouped stones in which two uprights support a crossbeam; later, the bluestones were re-erected. The monument that these builders left behind in an astonishing tribute to their imagination and skill.

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