After all the time spent driving over the past few days, the GNU decreed that he wanted to go somewhere local. So, after poring over the Ordnance Survey book of walks for the area (well worth getting) we found a nice local walk around the village of Llangynidr.
The walk took us down and along the River Usk, at times scrabbling along a narrow path against the cliff face, before heading up and back down the towpath of the Monmouthshire and Brecon Canal. The promised waterfall was a bit disappointing, but we got a surprise treat in the form of a jet fighter out to play (possibly a Tornado). They often practice low-level high-speed flying around the Brecon Beacons, and this one did a couple of circuits before vanishing into the distance.