And a 4th. Maybe not as much fun, but in Canada we have a TransCanada trail that is 75% complete, and is slated for completion by Canada's 150th Birthday in 2017. The trail is currently 17,000 kilometers (10,563 miles)long and when complete will be 24,000 kilometers (14,912 miles)long. I've asked that the TB stick to the trail, and cross this great country of ours, dipping and dropping in caches along the way.
It's kind of a fun adventure, because it means learning the path of the trail. I haven't let go of it yet, because I'm still busy taking it to the caches in British Columbia.