A466 road about long and runs through the counties of Herefordshire and Gloucestershire in England, and Monmouthshire in Wales. It runs south from Kingsthorne, on the A49 south east of Hereford to Monmouth, crossing the A40. After crossing the River Wye at the Wye Bridge, Monmouth and Bigsweir Bridge near Llandogo, it follows a picturesque route south down the Wye valley through Tintern and Chepstow to the M48 motorway at junction 2. The road crosses the border between England and Wales at three places along its length: at Buckholt, Redbrook, and Bigsweir. It runs through an Area of Outstanding Natural Beauty, and
Wye Valley Walk Hafren, having passed within viewing distance of the source of the River Wye on Plynlimon near Aberystwyth, a total of . The Wye Valley Walk is marked out by circular yellow waymark arrows, finger posts, and signs showing the path's logo, a leaping salmon. Most of the route follows Public Rights of Way. Some parts are permissive paths where owners have agreed for them to be used. Parts of Plynlimon are open countryside in which there is a right to roam established by the Countryside and Rights of Way Act 2000. The route passes through Chepstow, the Wye Valley AONB,