Taking the walk from south to north, it runs from Valleyfield Monument to Loanhead and back to Rosslyn, around 7 miles. For much of the walk you are following a disused railway track, providing good walking conditions on the whole. The points described can be followed on the map. If you have access to more than one vehicle, you can leave one at Rosslyn for when you finish. Otherwise, there are buses through Penicuik and Bonnyrigg. Map is O.S. Sheet 66.
A. The winding river North Esk flows beneath and alongside the walkway where you start at Valleyfield Monument, near Penicuik. The Monument stands at the edge of an old paper mill and marks the grave of 309 French prisoners of war, who were imprisoned here during the Napoleonic wars.
From here, you pass the old Eskbridge Station and, a little beyond, you come to a tall metal gate on the left of the track.
B. Pass through the gate, taking the path leading to Beeslack Woods. The woods contain a mixture of native and ornamental trees and shrubs, planted in the old estate manner, and many wild flowers. Return to the walkway along the same track.
C. Auchendinny Station is one of several access points to the walkway, all well signposted. It was once a busy station that stood near an interlocking arrangement if two bridges and a tunnel shaped like a bowstring. Follow the trail through the Firth Tunnel.
D. From the tunnel, you will emerge onto the then span Firth Viaduct. This brick structure was designed by Thomas Bouch, who also designed the Tay Bridge.
Views from here are spectacular. The rolling Pentland Hills rise from the west and the River North Esk flows below. Some way over to the left, perched on a rocky promontory high above the river, is the 17th Century Woodhouselee Castle.
After crossing the viaduct, you enter what is known as the Tin Tunnel. This tunnel runs for around 200 yards and was built to prevent sparks from train and engine wheels igniting the gunpowder stores at Kirkkettle Mill. From here, continue until you see an access point sprout off to your left.
E. Follow the path uo the north embankment to a grassy slope. At the foot lies the River North Esk and the heart of Roslin Glen Country Park. Only the ruins are left of what was once the gunpowder mill and many small birds and animals, including deer, have made it their domain. The main track that winds its way through the woodland leads to the Rosewell -Roslin road.
Retrace your steps to the walkway and visit the opposit bank of the Esk. Continue towards Hawthornden Crossing, passing what was once Roslin Castle Station, walk under the next bridge and you will arrive in the Roslin Glen Scottish Wildlife Trust Reserve, famed for its broad leaved woodland.
F. Meandering through the reserve, you may see mink, fox or stoat. The mainly oak and hazel woodland has over 200 species of flowering plants, 60 species of breeding birds and a rich lichen flora.
G. At Hawthornden Crossing, turn left to leave the walkway, rather than going straight on to Bonnyrigg. Go down Polton Road and, on the left, about 500 yards from the crossing, you will come to the gateway to Hawthornden Castle, a writer’s retreat where Ian Rankin and others have rescued their works. Walk along Polton Road, keeping Midfield House on your right and, at the foot of Midfield’s exit drive on the left, there is a relatively unknown track which lies between two cottages and leads to Polton Village.
H. In Polton, turn left and cross the bridge at the foot of the hill and you will see two footpaths. Take the path on your left which leads you high above the Glen where you can explore the wild side of the River.
A short distance up the Glen, you may glimpse Hawthornden Castle, standing on a sheer sandstone cliff, towering at least 150 feet above the River. There are many waterfalls in this part of the Glen and many caves. Little has changed since Sir Walter Scott so admired the Glen.
Stay on this path to reach the mysterious Roslin Chapel and Roslin Castle. You can visit the attractions or have a cup of tea in the tearoom before returning home.