The Green Cyclist Belt of Madrid is a 40 mile multi-use path around the municipality of Madrid. It’s like a cycling/walking “beltway”. The red asphalt path is well maintained with divided lanes for bikes and pedestrians. The part of the path that is closest to Madrid’s center skirts the eastern section of Casa de Campo. Depending on where you are staying, pick up the path from one of the various metro stations along the way (there is a station every 3 miles or less). If you need a rest, no worries, there are 45 resting 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.