The Green Cyclist Belt of Madrid is a 40 mile multi-use path around the municipality of Madrid. This red asphalt path is well maintained, with divided lanes for bikes and pedestrians. The closest part of the path to Madrid’s center skirts the eastern section of Casa de Campo. Depending on where you are staying, pick up the path from any of the metro stations along the way (there is a station every 3 miles or so). If you need a rest, there are areas equipped with benches, fountains, path maps, and trees to provide shade. Run for as long as you desire and take the metro back to the start.