Long-awaited plans for a road tunnel past Stonehenge have been finalised by the government.
The proposal for a 1.8-mile (2.9 km) dual carriageway tunnel is aimed at easing congestion on the nearby A303.
Transport Secretary Chris Grayling said the proposal will “transform’ the road and benefit people by “cutting congestion and improving journey times”.
A public consultation aimed at drivers and residents will run until 5 March.
The tunnel plans form part of a £2bn government scheme to upgrade all remaining sections of the A303 between the M3 and M5.
Highways England’s Jim O’Sullivan said: “Our plans for the A303 recognise the national importance of the route and these improvements will bring real benefit to the region and local communities.
“The public exhibitions will provide an excellent opportunity to explain further our plans and to hear feedback from stakeholders on our proposals to deliver the scheme.”
A report by UNESCO and the International Council on Monuments and Sites has recognised the benefits of the project.
At the moment the busy A303 passes within a few hundred metres of the ancient monument.
However, campaign group Stonehenge Alliance believes any tunnel shorter than 2.7-miles (4.3 km) would do “irreparable damage to the landscape”.
In 2015 it launched a petition calling for a longer tunnel which gained 17,500 signatures.
A spokesperson said: “The Alliance does not advocate new road building at Stonehenge but accepts the need to improve the tranquillity and appearance of the World Heritage Site and its setting.
“If the government insists on widening the A303 by means of a tunnel it must be sufficiently long to avoid any further damage to [Stonehenge] and its setting.”
English Heritage and the National Trust have also given their support to the option of “the longest tunnel possible”.
Chairman of Amesbury Museum and Heritage Trust Andy Rhind-Tutt described the tunnel plan as a “self-destructing time bomb” which would “do nothing” for traffic problems in the area.