Pioneering map of Japan found in Library of Congress

Almost 200 years ago, Japanese geographical surveyor Ino Tadataka made the first detailed map of Japan. The original was lost in a fire, but now an almost complete copy has been found in the Library of Congress. The full story from the Japan Times. (It\’s so cool that it\’s actually dated tomorrow [Saturday]).
I\’m always intrigued by these stories, like the Lincoln flag, of things being \”found\” in libraries. Where were they? Didn\’t anyone know they were there?