In 1963, Jerry Gretzinger started drawing a map of an imaginary world. "The map began as just a doodle," he says. But from that doodle, he just kept adding more. Eventually he made a complex spreadsheet to track the progress of the map and deal with its incredible growth. Over more than 50 years, the map has grown to wild proportions. It now covers more than 3,200 panels. Each panel is periodically copied, archived, and redrawn, so it's common to see panels that have been through dozens of "generations," changing along the way.
Back in 2009, Gretzinger was featured in a short documentary about his map. Have a look, and just start thinking about what it would take to maintain any art project for more than 50 years. My favorite part is around 6:40 when Gretzinger describes the "Void Defense Wall," a sort of bulwark against entropy within the map. Enjoy: