Campaigners on Monday lost a legal challenge to stop a controversial road tunnel near the prehistoric UNESCO World Heritage Site of Stonehenge in southwest England.

Druids, who celebrate the pagan solstice festival at the site each year, in December joined protesters outside London’s High Court.

Opponents of the £1.7 billion (€2 billion) project had pointed to planning officials’ assessment that it could cause ”permanent and irreversible damage” to the site, which has had UNESCO world heritage status since 1986.

"Highways officials argue that the project to upgrade the A303, a busy trunk road, will ease traffic congestion around the site"

But in a 50-page ruling, a High Court judge said ministers had “rightly focused on the relevant policies” and that the campaigners’ evidence “provides no basis for undermining that conclusion”.

Judge David Holgate largely dismissed the campaigners’ claims, finding parts of their case “unarguable”.

The Save Stonehenge World Heritage Site group, bringing together archaeologists and campaigners, had earlier successfully argued against the proposals.

The High Court rejected the plans in July 2021, citing concerns about the environmental impact.

But the government approved the scheme again in July 2023, prompting the latest legal challenge by campaigners in December.

Demonstrators during a protest outside of The Royal Courts of Justice on December 12, 2023, during a hearing for Save Stonehenge World Heritage Site's legal challenge against a decision to approve a controversial road project. Photo: Adrian Dennis / AFP

Highways officials argue that the project to upgrade the A303, a busy trunk road, will ease traffic congestion around the site.

Built in stages between around 3,000 and 2,300BCE, Stonehenge is one of the world’s most important prehistoric megalithic monuments in terms of its size, sophisticated layout and architectural precision.