<http://schema.org/keywords>
"city, dusk, green, kansas city, light, long exposure, missouri, night, nikon, ryan heffron, sigma, skyline, st patrick, union station, zoom, 300k"^^<http://www.w3.org/2001/XMLSchema#string>
<https://marketplace.500px.com/photos/28402173/kc-skyline-burst-by-ryan-heffron>