All background trained images are taken from The Book of Life and Coco, both films featuring Day of the Dead holiday theme. Various scenery such as town, city, unique indoors architecture, and more.
Here are a few tags for suitable background detail:
cityscape, building, fantasy, sky, cloud, tower, night, neon lights, detailed background, skull, city lights, candle, night, night sky, star (sky), detailed background, boardwalk, window, architecture...
Here the few imagines that were trained: Outdoors