The road then passes by Solstice Park and Bulford Camp before bypassing Amesbury and entering the Stonehenge World Heritage Site.

Between Ilchester and Shores Bridge (over the River Parrett, east of South Petherton) the road follows the course of the Roman Fosse Way.

It passes through the Blackdown Hills as a narrow road following the contours of the land, with the exception of a dual-carriageway bypass of Marsh.

[11] The end of the A303 is reached where it joins the A30, which enters as a side road and continues as the main route for Honiton and Exeter.

Portions of it follow the Harrow Way, an ancient trackway across Wessex that is one of Britain's oldest roads, reportedly being used as long ago as 3,000 BC.

Several historic roads converged at Weyhill, which is believed to have hosted a popular market since the Middle Ages, eventually becoming one of the most important in England by the 19th century.

[18] The modern course of the A303 was designed in the early 19th century as the "New Direct Road" by William Hanning, chief engineer of the Ilminster Turnpike Trust, in order to improve coaching traffic to southwest England.

Along with engineer Goldsworthy Gurney, Hanning attempted to design a steam-powered coach that could be run along the New Direct Road.

Ann Nelson's "Exeter Telegraph", a coach from London to Devon via the New Direct Road, could travel from Piccadilly to Devonport in a little over 21 hours.

Along with many other turnpike routes, the New Direct Road fell into disrepair during the 19th century owing to a lack of funds and available staff.

[28] In 1971, the Environment Secretary, Peter Walker announced the entire length of the A303 would be upgraded as part of a new roads programme that would deliver 1,000 new miles of motorway by 1980.

[30] By the mid-1980s, the A303 had been extended from its original fork by Micheldever Station, next to the A30, eastwards to meet the M3 motorway, and was a completely uninterrupted dual carriageway westwards as far as Amesbury.

[31] Ilminster was bypassed around this time; however the new road was built as single carriageway with 3 lanes, which caused a serious safety hazard leading to several fatal accidents.

During the so-called "Battle of Stonehenge" on 1 June 1985, where 520 people clashed violently with police, roadblocks were set up over a 10-mile (16 km) radius around the site.

[38] Conflicts were repeated for several years in the 1980s; in 1988 a van overturned on the A303 after leaving a clash with police at Stonehenge, killing one passenger and injuring ten others.

[40] The Government's Road Investment Strategy has committed to upgrading all the remaining single carriage sections of the A303 as far as Ilminster.

Highways England have made numerous proposals to improve the road, and it is currently identified under several Nationally Significant Infrastructure Projects.

[46] Although the new Labour government cancelled many road schemes after coming to power in 1997, there was still general support for a tunnel at Stonehenge.

A hearing concluded that transport secretary Grant Shapps had "acted irrationally and unlawfully" by backing the project and failed to properly assess the environmental impacts of each asset on the Stonehenge World Heritage Site as required by planning law.

Campaigners for the Stonehenge Alliance welcomed the decision, but Historic England expressed frustration over the "missed opportunity to remove the intrusive sight and sound of traffic past the iconic monument".

[54] The village of Winterbourne Stoke is immediately west of the World Heritage Site, and proposals to upgrade the A303 in this area have generally provided a bypass for it.

[56] The scheme was the subject of a public consultation in March 2007, and incorporated plans to widen the Ilminster bypass from South Petherton to a dual two-lane road.

[60] A number of other schemes for the remaining below-standard parts of the A303 were considered in the 1990s, including improvements west of Ilminster towards Marsh, and the single-carriageway section around Yeovilton.

[64] In 2016, Devon County Council announced they would self-fund improvements to the A303 between Ilminster and Honiton, which was not included in Highways England's list.

[69] Prior to the broadcast of Series 15 of Top Gear in 2010, the cast of Jeremy Clarkson, Richard Hammond and James May were spotted and recorded driving along the A303 in what appeared to be house cars.