The road starts on the western side of town at a roundabout on the A468 and A469 and heads east along Nantgarw Road. The road passes a retail park and a couple of housing estates but few buildings as yet front onto it. After crossing a set of traffic lights, where we meet a branch of the B4263, the road does indeed become built-up. We go under the Rhymney Line by Aber station and shortly skirt the grounds of Caerphilly Castle. We pass a large expanse of grass, with the castle and lake surrounding it visible beyond.
At the end of the grass traffic lights are reached, which marks the start of a gyratory where we cross the mainline of the B4263. Eastbound traffic simply continues ahead but westbound traffic has to go the long way round, although you get a better view of the castle this way. We now head northeastwards along Bedwas Road, which remains built-up for its entire length. The road soon ends at a roundabout, where it returns to the A468.