Twr Pen-cyrn [Mynydd Llangatwg]

This windswept limestone plateau offers a rugged contrast to the grassy peaks of the central Beacons. Topped by a trig point and two ancient Neolithic cairns, the summit provides clear sights across the Usk Valley towards the Sugar Loaf and the dark, flat-topped ridges of the Black Mountains.

• •The name Twr Pen-cyrn translates from Welsh as the ‘Tower of the Peak of Cairns’, a literal reference to the two substantial Neolithic burial mounds that sit alongside the modern trig pillar.
• •This summit marks the eastern high point of the Mynydd Llangatwg plateau, a vast upland that sits directly above some of Britain’s longest and most complex cave systems, including the famous Ogof y Daren Cilau.
• •From the trig pillar, the view to the north is exceptional, looking down into the Usk Valley and across to the distinctive shark-fin profile of the Sugar Loaf and the long ridge of the Black Mountains.
• •The eastern edge of the hill drops steeply into the Clydach Gorge, where 19th-century quarrymen removed vast quantities of limestone for the Blaenavon ironworks, leaving behind the isolated 'Lonely Shepherd' rock pinnacle.
• •The plateau is so thoroughly pockmarked with shakeholes—natural depressions in the limestone—that navigating it in thick mist is a masterclass in why 'as the crow flies' is a phrase rarely used by walkers with intact ankles.