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
England–Wales border 1972. Whether Monmouthshire was part of Wales, or an English county treated for most purposes as though it were Welsh, was also settled by the 1972 Act, which included it in Wales. The modern boundary between Wales and England runs from the salt marshes of the Dee estuary adjoining the Wirral Peninsula, across reclaimed land to the River Dee at Saltney just west of Chester. It then loops south to include within England an area southwest of Chester, before rejoining the Dee, and then loops east of the river to include within Wales a large area known as Maelor, formerly