There's a mysterious pedestrian bridge over I-5 in North Seattle, with nothing like it for miles. After reading this post I looked it up in google maps, and sure enough, it's right next to an elementary school. https://www.google.com/maps/@47.7639358,-122.3249609,554a,35... And two similar ones over I-405 https://www.google.com/maps/@47.6594203,-122.1842507,174a,35... https://www.google.com/maps/@47.6768724,-122.187362,187a,35y...