This image was acquired from
flickr. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
blackandwhite monochrome black and white The .Foot HighSpeed Tunnel located in theFoot HighSpeed Tunnels central courtyard was dwarfed by its host. Note the tunnels simple construction the hoist frame over the circular fan section with man kneeling on top and the airexchange tower to the right of the fan section. The .Foot HighSpeed