The Vennbahn railway used to run through the wild Hautes Fagnes region of Belgium carrying raw materials to Germany.
It closed down in 2008, leaving behind abandoned tracks and empty stations. But an ambitious project was launched in 2013 to turn it into a cycling and walking trail.
The route now runs for 125 kilometres between Troisvierges in northern Luxembourg and Aachen in Germany, taking in dark pine woods and desolate stretches of the Fagnes.
One of the best sections runs from the abandoned station Sourbrodt Gare to the pretty valley town of Monschau in Germany.
You can find bike-friendly places to stay along the route in converted farmhouses, country inns and small hotels.
Derek Blyth’s hidden secret of the day: Derek Blyth is the author of the bestselling “The 500 Hidden Secrets of Belgium”. He picks out one of his favourite hidden secrets for The Brussels Times every day.