Herbert Smith has landed the unusual brief of advising English Heritage as it co-ordinates a Private Finance Initiative project at Stonehenge.
Adrian Clough, partner responsible for the project, said: "It is not often you are given the opportunity to be involved with a stone circle set up around 2000 BC, which predates ancient cities in Mesopotamia and Egypt."
The PFI project is part of English Heritage's Stonehenge Millennium Scheme which aims to build a new visitors centre and transport link some distance from the stones.
The construction part of the Millennium Scheme, which also involves creating a new archaeological park near the stones, will be put out to tender to construction companies.
The need for a new visitor's centre at Stonehenge was highlighted in a recent report by a parliamentary committee. It described the present centre as a "national disgrace".