"Offers startling revelations about sites we think we know; Valley, Forge, Abraham Lincoln's log cabin, the Intrepid. It also tells of new sites, events, and individuals that should be commemorated on the landscape but aren't; a tombstone with a story to tell in Mississippi, a spy in the confederate White House, the unforeseen fallout from the first nuclear missile test, the reverse underground railway, a modern "sundown" town (blacks can work there,...