Ben Fry's classic map of the United States,"All Streets," demonstrated that a complete map of streets also implicitly creates a map of the topography around them, because the form of the land determined the locations of the roads. Few places in the world show this effect as strongly as Japan, where intensive urbanization constrasts sharply with the surrounding rugged terrain.
Even though Japan has been thoroughly mapped in OpenStreetMap for several years, the map continues to be refined every day. Only a handful of roads, shown in blue, have been untouched since 2007. The other colors progress in time from purple in 2008 through red in 2010 and orange in 2012 to yellow roads that have been edited in the past year.