Spectacular first day cover celebrating the 100th Anniversary of baseball with a Centennial graphic including the bust of Abner Doubleday. This historic piece was postmarked June 12 of 1939 in Cooperstown, New York, which was the very first day of operation for the newly-christened National Baseball Hall of Fame and nearby Doubleday Field.

As if that isn't already as good as it gets, this example has been signed in blue ink by Ted Williams, considered by many to be the greatest hitter who ever lived.

Authenticated by PSA/DNA, this is a tremendous piece.