<http://schema.org/keywords>
"drewton, tunnel, yorkshire, hull, light, green, uk, england, nature, hidden, secret, urban, railway, abandoned, bridge, trees, grass, dark, bright, shadow"^^<http://www.w3.org/2001/XMLSchema#string>
<https://marketplace.500px.com/photos/18064133/tunnel-by-rich-rushton>