For the first time in more than a century, the enigmatic monument of Stonehenge may soon loom large over a sweeping English countryside devoid of roads and vehicles.

The U.K. government's Highways England agency has given approval to route the A303 expressway, which passes extremely close to the prehistoric icon, through a 1.8 mile-long tunnel under the Stonehenge World Heritage Site. The $2 billion-project would significantly reduce the traffic congestion that has increasingly become a modern eyesore in front of the idyllic landmark.

"A tunnel near Stonehenge will remove the traffic blight on local communities and enhance the famous landmark," the Department of Transport said in statement. "It will reconnect the two halves of the 6,500 acre World Heritage site which is currently split by the road, and remove the sight and sound of traffic from the Stonehenge landscape."

A before and after rendering of how the removal of the A303 expressway would appear from Stonehenge itself. A before-and-after rendering of how the removal of the A303 expressway would appear from Stonehenge itself. (Photo: Highways England)

As shown in the video below, the underground expressway would pass much further away from the monument than the current A303, avoiding important archaeological sites and providing an unobstructed view of the setting sun from Stonehenge during the winter solstice. For the first time in decades, visitors would also be able to walk the full length of "The Avenue," a ceremonial approach to Stonehenge from the river Avon dating back thousands of years.

As expected with anything that might impact a World Heritage Site, not everyone is thrilled with the idea of a tunnel passing near one of the U.K.'s most treasured cultural icons. In a July 2017 report to the World Heritage Committee, UNESCO decried the current plan, saying that it "is not considered satisfactory to suggest that the benefits from a 2.9km tunnel to the centre of the property can offset significant damage from lengths of four lane approach roads in cuttings elsewhere in the property."

Groups like the Stonehenge Alliance, a consortium of non-governmental organizations, share this concern, adding that expressway cuttings and other construction aspects of the project might irrevocably impact other important sites from the Neolithic and Bronze Ages.

"We are shocked at Highways England’s indifference to UNESCO’s advice," the group shared in a statement. "The project needs a complete re-think, not a minor tweak which still threatens major harm to this iconic landscape. The potential risk of loss, along with Avebury, of Stonehenge’s World Heritage Status casts shame upon our country and those responsible for caring for our heritage."

The approach to Stonehenge in the 1930s with the A303 on the left and the now-closed A344 on the right. The approach to Stonehenge in the 1930s with the A303 on the left and the now-closed A344 on the right. (Photo: UK National Archives)

For others such as Dan Hicks, a British archaeologist and anthropologist, the removal of the A303 expressway conjures "the illusion of an unchanging Neolithic relic" and rejects the unfolding story of the site through the ages. It would also end a modern opportunity for the millions of motorists who pass less than 600 feet from the monument to connect with a piece of cultural heritage; effectively rendering Stonehenge an exclusive engagement for paying customers.

"Hiding the road from the stones would hide the stones from the public," he writes. "Some 1.3m people will pass through the Stonehenge giftshop this year, but perhaps ten times that number will witness the monument from a passing vehicle. Those thrilling, often unexpected views may not be celebrated among the iconic experiences of global prehistory, but they are surely among the most democratic."

A map showing the proposed placement of the 1.8 mile-long 'Stonehenge Tunnel' through the World Heritage Site. A map showing the proposed placement of the 1.8-mile Stonehenge Tunnel through the World Heritage Site. (Photo: Highways England)

While opponents are against the tunnel, they're in full support of the need to do something to remedy the congestion plaguing the A303. The single-lane road, one of the main routes from London to South West England, sees upwards of 30,000 vehicles per day. Alternatives to the tunnel proposed by groups like the Stonehenge Alliance include everything from lengthening the tunnel to nearly 4 miles to encompass the full expanse of the World Heritage Site to turning the A303 into a westbound one-way road.

"The landscape would look much as it does now but without the jams," suggests Simon Jenkins for The Spectator. "Motorists would continue to get an uplifting glimpse of their past. The Wiltshire hillside would be scarred but it would not be torn open. Millions of pounds would be saved."

The project will now head into a lengthy planning phase, with construction on the new underground route not expected to begin until sometime in 2021. Should the work proceed without the discovery of new archeological sites or other possible delays, the Stonehenge Tunnel is expected to be completed by 2029.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.