You can of course see many Roman roads across Britain today, because they have remained in use over many hundreds of years. Watling Street, for instance, is now the A5, and the Fosse Way - the original Roman road from Exeter to Lincoln - can still be followed across the country.
What's special about the Roman road at Ackling Dyke is that it hasn't been developed into a modern road, and exists now as a track way. It travels straight for several miles towards the hill-fort at Badbury Rings, and as the whole of this part of the road is right of way, it makes a pleasant and evocative walk.
What you can see clearly at Ackling Dyke is the raised "agger". Like an embankment, the foundations of the road have been built up so that the road actually runs several feet above the surrounding fields. The idea of the agger is to provide drainage, but it's also been argued that by making the road so visible, it would be another statement of Roman authority, intended to impress and intimidate the natives.
To find Ackling Dyke, travel along the A354 from Blandford towards Salisbury. Take a right turn onto the B3081, travelling in the direction of Ringwood and Ackling Dyke is a quarter of a mile along that road on the left. Park in the lay by and walk down footpath to the remains.