I want to thank Reuben for posting Utilizing the Space Beneath Bridges
Since I cannot put images in comments, I will post these as further examples, from Borough Market, London, Brixton, and the Darling Harbour, Sydney, respectively. The first three pictures are under railway bridges, the last a freeway bridge.
Borough Market – London
Borough Market, London
Brixton, London – Shops in the Viaduct
Carousel in Sydney, Australia
Check out the Brooklyn Banks (actually in Manhattan). Another example of skateboarding under a bridge, although this was built as a park and skateboarders ended up adopting it as their own.
This is by far my favorite under freeway use (I’m biased because I’m a mountain biker). I’ve always thought under 394 would be the perfect place for this.
Colonade bike park in Seattle: http://trails.evergreenmtb.org/w/index.php?title=Trail:I-5_Colonnade