Stonehenge is a monument megalithic type crómlech , late Neolithic ( XX century BC. ), Located near Amesbury in Wiltshire, England , about fifteen kilometers north of Salisbury .
The megalithic complex of Stonehenge, Avebury and related sites was proclaimed a World Heritage Site by Unesco in 1986 .
Stonehenge is formed by large blocks of metamorphic rocks distributed in four concentric circles. Outside, thirty meters in diameter, is made of large rectangular stones of sandstone which were originally topped by lintels also of stone, leaving only seven today in the same place. Inside this outer row lies another circle of smaller blocks of bluish sandstone.
This encloses a horseshoe-shaped structure built with sandstone stones of the same color. In its interior remains a slab of micaceous sandstone known as "the Altar".