Almost 100 of Dorset's Highway Structures are recorded as having listed building status and 17 are classified as scheduled monuments. Of these, twelve are thought to be medieval and 16th century. It is not known which is the oldest but it is understood that a structure has spanned the River Stour at White Mill, Sturminster Marshall since 1174.

A well known feature on many of the County's older bridges is the 'Transportation for Life Plate'. These plates were fixed to a number of bridges around 1828 following an Act of Parliament that gave the courts the power to transport, for life, vandals found guilty of damaging a bridge. Good examples of these plates can be seen today on Grey's Bridge in Dorchester and Durweston Bridge over the River Stour.

Another historic plate that can be seen fixed to some of Dorset's bridges warns the owners of 'locomotive traction engines and other ponderous carriages' against using the bridge.

Dorset's older structures form an important part of the County's history and require special attention to ensure that they are sympathetically maintained. Consent from the Department of Culture Media and Sport is usually required before any works are undertaken. Historic lime based mortars and stone or bricks to match the existing are used in cases where repairs are necessary.