Protesters have taken part in a “mass trespass” at Stonehenge to oppose plans to dig a tunnel near the monument.
The group, made up of local residents, ecologists, activists, archaeologists and pagans, gathered at the Wiltshire site at about 12:00 GMT on Saturday.
English Heritage closed the site until Sunday and said it was an offence to enter without permission.
Transport Secretary Grant Shapps approved the £1.7bn scheme against the recommendations of planning officials.
Campaigners are worried that the work will have a detrimental impact on the wider Stonehenge world heritage site.
They said they gathered in support of Save Stonehenge World Heritage Site, which has launched a legal challenge against Mr Shapps’ decision.
Environmental activist Dan Hooper, known as Swampy, said: “This is the coming together of people who are saying we have had enough.
“The Stonehenge tunnel is just one scheme in a £27bn roads programme.
“As road transport is the single largest source of carbon emissions in the UK, this is insane.”
He added: “Building more roads simply leads to more traffic and carbon. We need to put a stop to these road schemes as we did before.”
In a statement issued on Saturday evening, Wiltshire Police said no arrests had been made and the event had “passed peacefully”.
The tunnel is part of a £1.7bn investment in the A303 between Amesbury and Berwick Down.
The A303, which is a popular route for motorists travelling to and from the South West, is often severely congested on the single carriageway stretch near the stones in Wiltshire.
Highways England said its plan for the two-mile (3.2km) tunnel will remove the sight and sound of traffic passing the site, and cut journey times.
However, Unesco previously said the scheme would have an “adverse impact” on the surrounding landscape.
Simon Bramwell, a pagan, described the site as “hallowed ground” and said the cost of the scheme would “be better spent elsewhere”.
A spokeswoman for English Heritage said: “It is an offence under the Ancient Monuments Act (1979) for people to enter the monument area without English Heritage’s permission..
“Whilst we respect people’s right to demonstrate peacefully, we do not condone behaviour that disrupts and endangers the site and the people who visit or work here.”