|Length:||14.2 miles (22.9 km)|
|Meets:||A40, B4347, B4293|
|Route outline (key)|
The B4233 is a rural B-road in Monmouthshire. It has the distinction of being the lowest numbered Class II road wholly in Wales in the 1922 Road Lists.
It originally started on the A465 Merthyr Road in Abergavenny and headed through town along Tudor Street and Lion Street. All this is now unclassified and so the road starts where it has always met the A40 Monk Street. It leaves town to the east along Lower Monk Street and soon crosses a bridge over the Welsh Marches Line with another over the A465 bypass immediately afterwards.
The road continues eastwards. It seems to hold its direction as more important than following the terrain and as such the first few miles are very hilly, with several ridges and valleys crossed in quick succession. One of these valleys contains the River Trothy and (after another climb) the road settles down to follow this river downstream for a couple of miles after Llantilio Crossenny.
At Onen the Trothy heads off southwards and so the B4233 climbs again in its eastward route. After going through The Hendre with its wood a dogleg descent brings it to Rockfield and a junction with the B4347.
After another mile the road enters the suburbs of Monmouth. It passes the famous fortified Monnow Bridge (which once carried the A48 but is now closed to traffic) before ending at the next set of traffic lights, where a new bridge carries B4293 traffic out of the town centre. The A40 Monmouth bypass is just ahead.