The third stage of Stonehenge, about 2000 BC, saw the arrival of the
Sarsen stones, which were almost certainly brought from the Marlborough
Downs near Avebury, in north Wiltshire, about 25 miles north of Stonehenge.
The largest of the Sarsen stones transported to Stonehenge weigh 50 tonnes
and transportation by water would have been impossible, the stones could
only have been moved using sledges and ropes. Modern calculations show
that it would have taken 500 men using leather ropes to pull one stone,
with an extra 100 men needed to lay the huge rollers in front of the sledge.
These were arranged in an outer circle with a continuous run of lintels.
Inside the circle, five trilithons were placed in a horseshoe arrangement,
whose remains we can still see today.