What is "bluestonehenge"

"Bluestonehenge" or "Bluehenge" (also known as "West Amesbury Henge") is a prehistoric henge and stone circle monument that was discovered by the Stonehenge Riverside Project about south-east of Stonehenge in Wiltshire, England. All that currently remains of the site is the ditch of the henge and a series of stone settings, none of which is visible above ground.