Of the glacially sculpted hills that surround Abergavenny, Skirrid (486m) is the most dramatic looking and has a history to match. A cleft in the rock near the top was believed to have split open at the exact time of Christ's death and a chapel was built here on what was considered a particularly holy place (a couple of upright stones remain). During the Catholic persecutions, as many as 100 people at a time would attend illegal Masses at this remote spot.
Begin your trek from Abergavenny, or take the B4521 to the car park at the base of the hill. It's a steep climb from here through the woods on a track that can be muddy; wear sensible shoes. Once you clear the tree line the walk is less steep, with a final climb right at the end to the summit where you'll be rewarded with extravagant views. From here you can return the way you came or continue down the other side to Llanfihangel Crucorney.