Along its route, the A120 bypasses the towns of Bishop's Stortford, Great Dunmow, Braintree, Coggeshall, Colchester and Dovercourt.

London Stansted Airport sits directly north of the route on the Essex and Hertfordshire border.

The route then continues towards Little Hadham, which it bypasses to the north, before reaching a roundabout with the A1184 and A1250 to the west of Bishop's Stortford.

The route continues to bypass the north-eastern portion of Bishop's Stortford before meeting the A1250 Dunmow Road, then the M11 motorway at junction 8.

Direct access to the A120 eastbound is provided from the M11 northbound at junction 8A, on a carriageway which passes over the top of Priory Wood Roundabout (and vice versa for A120 westbound/M11 southbound traffic).

The A12 runs southbound towards Kelvedon, Witham, Chelmsford and London, and northbound towards Colchester, Ipswich and Felixstowe.

Marks Tey railway station, on the Great Eastern Main Line between London and Norwich, lies directly north-west of the junction.

The remainder of the A120 sits to the east of the A12 between Colchester and Harwich, meeting the London to Ipswich road at junction 29.

The A133 meets the A120 at a junction between Elmstead and Wix, which carries traffic towards Great Bentley, Weeley and Clacton-on-Sea.

[4][5] According to the Society for All British and Irish Road Enthusiasts (SABRE), the Ministry of Transport's 1922 List of Class I and Class II Roads and Numbers listed the A120 as being the route Puckeridge – Bishop's Stortford – Great Dunmow – Braintree – Marks Tey.

Oxford Archaeologists, leading the project, described as a "once-in-a-lifetime discovery" and said evidence suggests the site was a major transport and trading post in the East of England.

Of Great Dunmow, a Heritage Gateway report notes:"Excavations between 1968 and 1972 uncovered the remains of a minor Roman linear settlement located along Stane Street, extending over 2 to 3 acres occupied from the 1st century AD to the 4th century AD; a Roman cremation cemetery and possible shrine were discovered along with timber buildings.