The walk starts from Dennis Knoll, a small Peak District National Park Authority car park where the Long Causeway leaves the lane north of Hathersage. It has just 10 spaces, and the Authority's car parks around Stanage often fill early at weekends and in the holidays, so arrive early and please don't park on the verges. It's Pay & Display with a contactless-only machine, or you can pay by phone with RingGo (location 51706). Charges apply from 9AM to 6PM every day. The Authority's current tariff is £3.40 for up to 2 hours, £5.50 for up to 4 hours and £6.60 for the day, so for a walk of 3 to 4 hours the all-day ticket is the safe choice. Blue Badge holders park free. There are no toilets here. Check the latest prices here.

Somewhere beneath the moor on this walk runs a tunnel 4.5 miles long. It was dug between 1903 and 1909 to carry water from the Derwent Valley, where Ladybower Reservoir is now, east through the hills to the Rivelin Dams above Sheffield. The Sheffield Waterworks Company had built the two Rivelin reservoirs in the 1840s, and the agreement that allowed them said they must let more than three million gallons a day into the River Rivelin for the mill owners downstream. For years much of that water had to be borrowed from the Redmires Reservoirs, so the tunnel was built to bring it from the plentiful River Derwent instead.

A tunnel dug through a hill has to be dead straight, so the engineers set out its line with a row of sighting towers across the moors. The tallest, about 40 feet high, stood on top of Stanage Edge at the halfway point. From it, surveyors sighted along the line to a stone pillar on Bamford Moor to the west and another near Oaking Clough to the east. The tower was later pulled down, and the heap of stones beside the edge path north of High Neb is all that is left of it. A small building nearby stored the surveying gear and may later have held blasting powder for the quarries at Stanage End. The pillar on Bamford Moor, about 8 feet tall, is the one you pass on the climb from Jarvis Clough.

The finished tunnel is 6 feet 6 inches high and 6 feet wide, and it falls just 2 metres over its whole length, a gradient of 1 in 3,600. An electric railway ran through it while it was being built, and it cost £135,151, about £13,000 less than the budget. The tunnel is unlined, so water seeps in from the moor along the way and more flows out at the Rivelin end than goes in at the Ladybower end. It still takes water from a drain hole in the south-east corner of Ladybower and delivers it into the Lower Rivelin Reservoir, which helps supply Sheffield.

The stony track you climb at the start of this walk is the Long Causeway, or Long Causey, a medieval packhorse road between Sheffield and Hathersage. Old maps marked it as a Roman road, because it was thought to follow part of Batham Gate, the Roman road from Templeborough to Buxton. In recent years scholars have doubted that, and in 2016 a report on University of Sheffield excavations near Ringinglow questioned whether there was any Roman road near Stanage at all.

In the Middle Ages, packhorses carried salt from the Cheshire salt mines along it into Yorkshire. From Sheffield the road climbed for seven miles and more than 1,100 feet to Stanedge Pole, on the boundary between the manors of Sheffield and Hathersage, then turned west and swung north-west to come down Stanage Edge through a less rocky gap. By the 18th century carts had taken over from many of the packhorses, loaded with oil, hardware, barrels of tar, hogsheads of treacle, glue from Manchester, lead and small grinding stones. The way down was so steep that carters asked their passengers to get out, and hung stones off the back of their carts to hold them back. At the bottom, the road swung right round past Dennis Knoll, where this walk starts, and into Hathersage from the north.

The causeway was never a turnpike, but it was busy enough to be given milestones in the 1730s, which was very unusual for a road without tolls. Traffic began to fall away around 1760, after a new route to the Hope Valley opened through Ringinglow. Today it survives as an unsurfaced track between Redmires Reservoirs and Dennis Knoll, still paved in places, with the longest paved stretch, about 80 metres, just west of Stanage Pole. Vehicles are now banned from it. When Derbyshire County Council resurfaced the stretch between the edge and Dennis Knoll in 2013 and removed many of its big boulders, plenty of people complained that the smooth new surface didn't suit such an ancient road.