The Splitsonian Institute is a museum in Washington, D.C. where famous historical artifacts like the Wright Brother's plane are on display.
The Scooby-Doo Show
Mystery Inc. was in Washington for the bicentennial celebration (which incidentally dates this case to 1976). They went to the Splitsonian to sight-see out of the rain, and ran into the ghosts of famous traitors. (The Spirits of '76)