Stonehenge was built around 4000.2000 B.C., probably the most famous prehistoric site in the world. This year, Stonehenge will celebrate its 100th anniversary. Around 2500 B.C., Stonehenge was built in the center of the site. Stonehenge uses two different stones - "large sandstone and smaller "blue sandstone". Around 200 or 300 years later, the blue sandstone was repositioned to form a circle (and then repositioned as a horseshoe). At the same time, a trail connecting Stonehenge and the Avon River was established.