From the start at Llanerch y Cawr carpark, cross the road down towards the river and cross the bridge. Follow the road up hill around a steep curve to the right before the barns. After about 100 yards a made up track (bridleway) goes off left through a gateway. Follow the track up Cwm Paradwys for nearly a mile to where it turns a hairpin to the left up hill. Follow the way marker and walk straight on along a sheep track with Nant Paradwys down to your right. Pass the cairn and keep following the sheep track, it can become very boggy in places. The stream meanders gradually more distant as you head up the valley.
After about a mile and a half you reach the head of the valley and a rather small stone circle, don’t expect Stone Henge! The Brecon Beacons come into view to the south and a hilltop cairn on the horizon to your right. Turn right at the stone circle and follow the very boggy path marked by the occasional concrete marker. The large cairns at Drygarn Fawr will soon come into view to the west about 2 miles away. Cross the boggy ground and head straight for it followings any sheep tracks heading generally in the right direction. The going is pretty awkward and difficult for a while with a few obvious paths and quite a few boggy and eroded peat areas. Beware of hidden quite deep holes. Keep heading for the cairns of Drygarn Fawr.
About half a mile from the cairns a very obvious track is met leading up the hill to the top (SN 862584). On a clear day the views are spectacular across the hills of Mid Wales and beyond to the Preseli Hill in the south west. A view span of nearly 100 miles is possible.
From the top (2100 feet) head north-east (again there are no paths) keeping the eroded peat areas to your left and the lower cairn and crags to your right. You soon come to a small stream in a valley (Nant yr Ast). Cross the stream and turn left following the sheep tracks down to the Rhiwnant valley. Follow the right hand bank of the Rhiwnant downstream along the trail. After about a mile the track bends around to the right opposite some old mine works.
After another half mile there are some more ruins of mine buildings either side of the river. Here do not take the made up track up the hill to your right, but go down left to join riverside sheep tracks. Carefully cross Nant Paradwys just above its junction with the Rhiwnant and continue along the Rhiwnant bank for another 100 yards before taking the path up to the right and joining the stone track you started out walking up earlier. Turn left down the hill and retrace your steps back to the car park.