The Swiss Federal Office of Topography (Swisstopo) has employed professional mapmakers for 175 years now. They plot out the topography of the country and record changes over time, such as growing cities and more accurate measurements. But every once in a while, an anomaly is found that show a cartographer's sly and subversive sense of humor.
Watching a single place evolve over time reveals small histories and granular inconsistencies. Train stations and airports are built, a gunpowder factory disappears for the length of the Cold War. But on certain maps, in Switzerland’s more remote regions, there is also, curiously, a spider, a man’s face, a naked woman, a hiker, a fish, and a marmot. These barely-perceptible apparitions aren’t mistakes, but rather illustrations hidden by the official cartographers at Swisstopo in defiance of their mandate “to reconstitute reality.” Maps published by Swisstopo undergo a rigorous proofreading process, so to find an illicit drawing means that the cartographer has outsmarted his colleagues.
Some of the illustrations were only discovered decades after they were embedded in the maps. Why would they do this? And how did the hijinks begin? For all we know, it's still going on. Read about the hidden pictures in Swiss maps at Eye on Design. -via Amusing Planet