The Springwater Corridor is a 30 mile long multiuse path , skirting the Southern edge of the city of Portland, and running east to the city of Boring.
The corridor, which is paved over all but the last few miles of its length, was previously a commuter railline, which went out of service in 1956, was acquired in 1990 and has been improved on since. The corridor is close to being finished, and when it is, it will blend in seemlessly with the 40 Mile Loop, the system of trails and greenbelts that encircles the Portland area.
The trail is suitable for biking on, and also for walking, although walking the entire length would take the better part of a day. The trail runs roughly parallel to Johnson Creek, and crosses many parks and natural spaces, including Powell Butte.
The technical explanation being given, my own personal experience of the trail is that it has the almost animeish quality of throwing disparate elements at you in quick succession, planting a mosaic that begins to make beautiful sense after a hundred blocks or so. The trail carries the walker or rider through the southeast side of Portland, not the trendiest or most beautiful of neighborhoods. Much of the urban parts of the trail is surrounded by light industry in various states of disrepair. The Eastern parts of the trail are in lands that are a patchwork of urbanized, rural, and wild. The trail presents both scenery and anti-scenery together. For example, as it runs through the city of Gresham, it passes a brick factory that has been abandoned to the elements, with acres of bricks with trees growing up between them.
In short, not only is the Springwater Corridor a great place to exercise or enjoy yourself; it is also, in the right frame of mind, an experience in the art of urban or post-urban collage.