The A303 redevelopment proposal had originally garnered the attention of preservation advocates beginning in 2017 and eventually yielded a favorable ruling from the UK High Court in 2021, the same year UNESCO first threatened to add the site to its list of World Heritage in Danger. 

Adding to the narrative, UNESCO has now openly criticized the UK government's recent decision to proceed with the contentious project. The UK's transport secretary, Mark Harper, sanctioned the scheme earlier this year, setting its initial cost at a staggering £1.7bn. This tunnel, which is proposed to be two miles in length, is alarmingly close to the ancient and revered site of Stonehenge in Wiltshire.

National Highways insists its plan will "conserve and enhance" the area while addressing a notorious traffic bottleneck. UNESCO’s requests center on placing the tunnel entrances at longer intervals so as to not disturb the site’s existing landscape. In a statement, the project manager for the overhaul said, “We will continue to work with the Heritage Monitoring Advisory Group and experts within the Scientific Committee to ensure the scheme is delivered with heritage and the Outstanding Universal Value of the World Heritage Site at the heart of every decision made.”

The requests were made the same week UNESCO added a total of 42 new sites, including three in Ukraine, to the World Heritage in Danger register.