|Length:||16.7 miles (26.9 km)|
|Meets:||A483, A488, B4357, B4355, B4362|
|Former Number(s):||B4362, B4355|
|Route outline (key)|
The B4356 is a medium-length B-road in east Radnorshire.
The road starts on the A483 in the valley of the River Ithon and climbs to the east along a narrow road through Llanbister and then out of the village into the hills. A cattle grid is soon crossed and presently the road reaches the top of the hill. It follows an undulating route through the fields of sheep before a steep descent takes it through The Pound (a hamlet), over the Camddwr (a stream) and across another cattle grid.
We climb again to the east and continue along a ridge before a winding descent takes us into the valley of the River Lugg. After going through the hamlet of Gravel we zigzag under the Heart of Wales Line and follow river and railway for about a mile. The road now becomes wide enough to have a central line for the first time but this doesn't last long. The railway line then bears off to the left and we continue along the valley, soon crossing the Lugg to reach Llangunllo, where we go along the narrow main street.
After another crossing of the river we continue downstream with an intermittent central white line, presently reaching a T-junction on the A488. There's a short multiplex to the right then the B4356 regains its number by turning left. S2 from the outset it continues along the valley but with the river slightly further away to the right. The road soon reaches Whitton where it is crossed by the B4357, then bears gradually round to the left to pass through Dolley Green and then cross the Lugg. There's a sharp left-hand bend on the far side.
We continue east, still almost in the valley bottom, before reaching Presteigne. On the near side of town the B4355 comes in from the left to start a short multiplex. The B4356 takes the next turn left, which is only accessible in this direction, to enter the traffic-calmed Knighton Road. At a T-junction the road TOTSOs left (a spur of the B4356 heads right to return to the B4355) and continues through the town centre and along the narrow (and one-way) High Street. There's another T-junction at the junction with Broad Street where we TOTSO right and the road becomes two-way. At a mini-roundabout another spur bears right back to the B4355 and again the main road continues ahead. We enter the suburbs and pass a recreation ground to end at a roundabout on the B4362. Although this final section through the town centre is part of the B4356 it is not signed and traffic is directed along the parallel B4355 instead.
Originally the road was numbered B4362 east of the A488 and unclassified to the west. In 1935, with the rerouting of the B4362 west of Presteigne the entire road was numbered B4356, with the exception of the section through Presteigne itself which became part of the B4355. When that road was moved onto the bypass the B4356 took on its old route.