Twr Pen-cyrn [Mynydd Llangatwg] is a 529m hill above Llangattock. It is topped by two large cairns and a trig point and has fantastic views in every direction.
There is a car park marked on the map that you can get to from two different directions and it has space for quite a lot of cars and gives you great access to this hill.
The path is very good at the beginning and generally solid all of the way up, but there are some distracting sheep trails that led me off of the main path a couple of times.
The cairns offer good shelter from any wind so this is a good hill to sit on for a while to enjoy the views, which are really impressive. A good walk.