Unesco has told the government to change its plans for a tunnel near Stonehenge or “not proceed” at all.
The United Nations’ cultural body said the world heritage site is at risk of being put on its “danger list” unless changes are made to the proposed £1.7bn scheme on the A303.
National Highways’ plans for the two-mile tunnel were approved by the government in July. It said the scheme is needed to tackle a “longstanding traffic bottleneck” around the site.