Time Team presenter Tony Robinson is joining campaigners protesting against plans to put a major road past Stonehenge into a tunnel.
Highways England is holding a public consultation on its plans for putting the A303 into a 1.8-mile (2.9km) dual carriageway tunnel where it passes the ancient stone circle to cut congestion and improve the surroundings.
The scheme is backed by English Heritage and the National Trust, who manage the area and believe it would make the setting of the stones more tranquil, give the public greater access to the wider prehistoric landscape and improve the environment for wildlife.
But opponents are concerned that the scheme, with a tunnel past the stones and a bypass to the north or south of nearby Winterbourne Stoke, would damage the World Heritage Site, which includes the stone circle and the wider landscape.
Some archaeologists have previously warned that recent significant finds - and much as yet undiscovered archaeology - could be lost or damaged if the Government presses ahead with the road-building plans.
The Stonehenge Alliance is staging a protest at the Society of Antiquaries at Burlington House, where Highways England is holding an event as part of the public consultation.
The alliance wants the consultation to be scrapped and re-run because they believe the options on the table would inflict severe damage on the World Heritage Site.
Robinson, who is joining the protest, said: "The primary criterion if road widening or tunnel building are required, must be that no further damage is done to this very special landscape."
Author and historian Tom Holland said: "The Stonehenge landscape, which is precious both for what we know and what we are yet to discover, is a millennia-old legacy to us.
"Do not let us be the generation that vandalises it irreparably."
And Kate Fielden, of the Stonehenge Alliance, said: "We want a genuine consultation with real choice.
"Both of Highways England's 'options' involve huge and damaging new roadworks gouged into our most important ancient landscape. Also, a seven-week consultation is far too short for this world-renowned site."
A report by the International Council on Monuments and Sites and United Nations cultural body Unesco found that putting the A303 past Stonehenge into a tunnel could benefit the World Heritage Site if the scheme is well designed and constructed.
The study, made at the request of the UK Government, warned that the position and design of the tunnel entrances, embankments, entry and exit ramps and construction works have the potential to adversely affect the historic landscape.
They would require rigorous investigation, evaluation, design and assessment, the report said - but with "good design and construction controls", the tunnel should have a beneficial impact on the World Heritage Site.