Step back into Roman and medieval Wales in this intriguing circuit around the Lledr Valley and little-known Cwm Penamnen, traversing sections of the Sarn Helen Roman road and visiting native Welsh Castell Dolwyddelan.

Start: Begin the walk in Dolwyddelan. There is free parking in the signed car park near Dolwyddelan railway station. Take the road

opposite the Post Office in the centre of Dolwyddelan; the car park is on the left immediately after the bridge over Afon Lledr.

Map reference: SH 737 521.

Distance: 9.5 kilometres/6 miles.

Duration: Allow 3-4 hours.

Difficulty: Moderate. Paths are generally good, with one steep section in the climb out of Cwm Penamnen.

Food and drink: Y Gwydyr Hotel, High Street, Dolwyddelan. Tel: 01690 750418. Also coffee from the Spar shop in the village centre.

Map: OS 1: 50,000 Landranger 115 Snowdon; OS 1:25,000 Explorer/Outdoor Leisure OL 18 Harlech, Portmadog & Bala.

The walk

1. Walk back to the road and turn left over the railway. Turn right immediately after the bridge and follow the road as it rises out of the village and into the hidden valley of Cwm Penamnen with the cascading river down to the left. As you enter the cwm the lane levels and you pass the excavated ruins of Tai Penamnen, a house dating back to the early 15th century.

This lane follows the line of the old Roman road which linked the forts of Caerhun in the Conwy Valley and Tomen-y-Muir near Trawsfynydd. Continue along the lane for about 1 kilometre/3/4 mile passing the track to 'Gwyndy', a farmhouse on the left.

A little further on and immediately before a cottage on the left ('Tan y Bwlch'), take the signed footpath on the right. This climbs steeply and directly up the hillside to a forest road. Across the road, the path continues to rise steeply through the trees. A stile at the end of the climb takes you onto the open hillside and you are treated to a grand view across the valley to the Moel Siabod, with the backs of the Glyderau and the Snowdon group to the left.

Follow the footpath ahead directly down the hillside. Lower down the path merges into a more defined farm track. Remain on this track, passing ruins (possibly 'hafods' or summer dwellings from earlier centuries) and going through gates.

Stay with the track until you can see a number of stone houses over to the left beyond a small valley and stream. A little further on, after the next gate enter a smaller field with house roofs visible ahead (roughly 200 metres away) and the castle on the far hillside. About 75 metres after the gate, take the signed footpath on the left (marked by small posts) to a ladder stile by a gate. Pass through a small field, then cross an old stone footbridge over the river.

The path now keeps close to the river on the right to eventually meet the road. Turn right to the A470.

2. Cross the road and follow the lane opposite, signed 'Roman Bridge'. This leads past Roman Bridge railway station, then over the railway and the river. Continue along the rising lane ignoring signed footpaths, first on the left, then on the right, until you reach a farm where the lane bends sharp left. Turn right here onto a signed footpath. At first you follow a track with gates and stiles then, where this bends left (about 500 metres), bear right as indicated by a finger post, onto a grassy path. Pass through a gate in a few metres then continue straight ahead on the obvious footpath.

Soon the castle comes into view and the path drops into a dip to join a concrete road to the left of, and a little beyond the castle.

Castell Dolwyddelan is one of the few native Welsh castles from the period of the independent Princes still in existence. Most castles built prior to the Edwardian Conquest were made from timber and have long since disappeared. In the case of Dolwyddelan, the original wooden structure was replaced by stone.

Follow the concrete road past the castle and where this turns sharp right go through the gate/gateway ahead and continue along an unmade lane to the road A470. Turn left and return to Dolwyddelan where a right turn at the Post Office will take you back to the car park to complete the walk.

This walk is taken from the book Walks in northern Snowdonia (ISBN 987-1-902512-06-8) by Carl Rogers, published by Mara Books ( Copies are available online or from local bookshops.