The A5 is a major road in the United Kingdom. It is also the first Roman built road in England hence the name Roman Road. It runs for about 260 miles (including sections concurrent with other designations) from London to Holyhead, following in part a section of the Roman Iter II route which later took the Anglo-Saxon name Watling Street.
The history of the A5 begins with Thomas Telford in the early nineteenth century. Following the Act of Union 1800, which unified Great Britain and Ireland, the government saw the need for improving communication links between London and Dublin. A Parliamentary committee led to an Act of Parliament of 1815 that authorised buying out existing turnpike road interests and, where necessary, constructing a new road, to complete the route between the two capitals. This made it the first major civilian state-funded road building project in Britain since Roman times.
Through England, the road largely took over existing turnpike roads, which mainly followed the route of the Anglo-Saxon Wæcelinga Stræt (Watling Street), much of which had been historically the Roman road Iter II.
From Shrewsbury and through Wales, Telford's work was more extensive. In places he followed existing roads, but he also built new links, including the Menai Suspension Bridge to connect the mainland with Anglesey and the Stanley Embankment to Holy Island.
The route through Wales retains many of the original features of Telford's road and has, since 1995, been recognised as an historic route worthy of preservation. These features include -
Starting at Marble Arch in London, the A5 runs north-west up the Edgware Road through Kilburn and Cricklewood. The A5 number disappears near Edgware, but the Roman Road continues as the A5183 through Elstree, Radlett, St Albans and Redbourn, to junction 9 of the M1, where it becomes the A5 again. From there on, it passes through Dunstable, where it crosses and briefly multiplexes with the A505. The stretch through Dunstable is mostly single carriageway with a 30mph speed limit and at-grade pedestrian crossings, and as a result serious traffic jams are frequent on this stretch. North of Dunstable the A5 passes through the village of Hockliffe, before becoming a dual carriageway and bypassing Little Brickhill. After a large roundabout with the A4146, the road becomes a fully grade-separated dual carriageway and passes through Milton Keynes. This stretch, known locally as the 'A5D', was built in 1981 and enabled the older route to be incorporated into the Milton Keynes grid road system. After passing Old Stratford, the dual carriageway ends at a large roundabout with the A508. The single carriageway then continues to pass through Potterspury and then Towcester. After crossing the A43 at a small roundabout, the road accompanies the Grand Union Canal and the M1 Motorway through the Watford Gap. As it passes close to Rugby the road is diverted slightly around the DIRFT complex which was built in 1997. The next phase to the Welsh border takes it through Hinckley before it bypasses the northern fringes of Nuneaton.After this the road formally passed straight through Tamworth, but a dual carriageway bypass has now been provided in a similar vein to the one in Milton Keynes (see above). From this point the road is a dual carriageway up until its junction with the M6 toll. After this junction it passes through Cannock and Telford, where it meets the M54 motorway. It then runs to Shrewsbury and Oswestry before entering Wales just west of Chirk. From the English border, it continues through Llangollen, Corwen, Capel Curig, and Bangor before arriving at Holyhead via a bridge between Wales and Anglesey.