Ключевые слова: abstract, art, background, city, clipart, colorful, concept, connections, cover, creative, curves, design, diagram, element, generic, graphic, grey, guide, illustration, knot, line, long, many, map, metro, modern, net, network, ornament, outline, pattern, perspective, plan, point, railway, repeating, scheme, shape, station, stylish, subway, tile, transition, transport, transportation, travel, tube, underground, urban, vanishing, wallpaper,