A classic motif for wallpaper is that of architecture, buildings, and architectural elements. Some are quite exotic, like "La Foire du Caire" (below), while others seem influenced by folk art (namely the Diamond Baratta print for Lee Jofa-actually a fabric rather than a paper but you get the idea). And some are so architecturally authentic, like the wonderful Adelphi ceiling paper below, that they blur the lines between reality and fiction.
"Oriental Toile" by Thibaut
Image above: Pillar and arch wallpaper panel fragment, from Old Manor House, Bourton-on-the-Water, Gloucestershire, England, c. 1769 (collection of Victoria and Albert Museum)