|Via:||Cross Inn, Temple Bar, Llanybydder|
|Length:||29.1 miles (46.8 km)|
|Meets:||A487, B4577, B4342, A482, A475, B4338, A485, B4310, B4302|
|Route outline (key)|
The B4337 is a lengthy 'B' class Road in mid-Wales.
The road starts on the A487 in Llanrhystud, only a short distance from the sea. It heads inland alongside the River Wyre for a short distance before climbing steeply out of the valley. Now heading south, the B4337 runs in an undulating fashion, with a maximum height of over 600 feet, to Cross Inn, where it is crossed by the B4577.
The road continues south across similar terrain. There is another steep climb through a wood to reach over 1000 feet, before the road descends to Trefilan. The B4337 is the dominant partner in a multiplex with the B4342 across the Aeron River. After the roads separate once again the B4337 climbs and then splits. The road ahead reaches the A482 to the south of Temple Bar. The right turn (which is badly signed) is the main line. It reaches the centre of Temple Bar and crosses the A482 at a staggered crossroads.
After a short distance the B4337 reaches the valley of a stream (which becomes the Grannell River) which it follows via Cribyn and Llanwennen (going round some very sharp corners en route). At Llanwennen the road crosses the A475 via a single mini-roundabout and short multiplex. Now following the valley of the River Teifi the B4337 goes through Alltyblaca before meeting the B4338 and crossing the river into Llanybydder. Here it crosses the A485.
After Llanybydder the B4337 follows the course of the Duar River then climbs through woods into the hills once more. After going through Rhydcymerau it then falls to Llansawel where it is joined by the B4310 before crossing a tributary of the River Cothi. The road then crosses a hill to cross the Cothi itself (the river follows a far longer course around the hill) before ending on the B4320 to the north of Talley.
Originally the B4337 ran only between Temple Bar and Llanybydder but by 1932 it had been extended both ways: south to Talley and north as far as its current TOTSO. The road from near Temple Bar to the coast at Llanrhystyd was originally numbered B4341; all this became an extension of the B4337 in 1935.