Largest trilithons

The largest trilithons are at Stonehenge, to the south of Salisbury Plain (United Kingdom), with single sarsen blocks weighing over 45tonnes and requiring over 550 men to drag them up a 9 degree gradient. The tallest upright stone is 6.7m (22ft) high, with another 2.4m (8ft) below ground. The earliest stage of the construction of the ditch has been dated to 2950BC.

Trilithon is a Greek word that means three stones. Stonehenge is a World Heritage Site owned by English Heritage, a conservation organization. Along with the National Trust (which owns 587ha of land surrounding the monument) is aiming to remove the nearby A344 road and improving the landscape around the stones.