<http://schema.org/keywords>
"europe, italy, tuscany, toscan, landscape, hills, rolling hills, travel, Architecture, Exterior, Field, House, Idyllic, Nobody, Outdoors, Rural Scene, Scenic, Sunlight, Tranquil Scene, Tree"^^<http://www.w3.org/2001/XMLSchema#string>
<https://marketplace.500px.com/photos/8056409/rolling-hills-by-csilla-zelko>