For two decades starting in 1955, millions of Americans spent their weekends listening to an extraordinary radio program--NBC's Monitor. Running continuously from Saturday morning through Sunday night, Monitor featured big-name hosts like Dave Garroway, Hugh Downs, Gene Rayburn, Ed McMahon, Henry Morgan, Barry Nelson, Joe Garagiola, Bill Cullen, Jim Lowe and Murray the K--all broadcasting from mammoth studios called "Radio Central."