Frederik den Femte, King of Denmark between 1746 and 1766, had a map collection that grew to more than 3500 plates in 55 volumes. Denmark’s Royal Library has scanned these plates and made them available online; a plugin is required to see them at maximum resolution. From the site: “The plates show maps, city maps with descriptions, prospects of cities and castles, palace gardens, drawings of fortifications, of army dispositions and cannons, satiric engravings and much more.” Thanks again to peacay.