The North Yorkshire Moors Railway is Britain's most popular heritage railway, and runs for 18 miles through the national park of the same name. The journey commences at the market town of Pickering, whose station has a recently restored overall roof. It continues through remote Levisham and into the spectacular glaciated gorge of Newtondale and onto Fen Bog, where George Stephenson floated the railway on a bed of sheep fleeces and timber. Once over Goathland summit, the line descends steeply to Goathland station, famous as both Aidensfield in Heartbeat and Hogsmeade station in the Harry Potter films. From Goathland the line drops at a continuous gradient of 1 in 49 to Grosmont, junction with the Esk Valley Railway and site of the busy engine sheds. Today, many NYMR trains continue to the coast at Whitby, a journey of 24 miles from Pickering, mostly on Stephenson's 1836 route.