This image depicts Pennant Day on June 12, 1906 at the Polo Grounds in New York. The Giants were celebrating their first World Series pennant and had just finished with their parade through New York, the first World Series parade ever held. The cars the players rode in are visible in centerfield just behind the ropes.
The large pennant is mounted on the rooftop behind home plate. The smaller pennants are seen suspended from the tops of the flagpole to the corners of the grandstand. The grandstand is profusely decorated with bunting and flags.
Interestingly, Roger Bresnahan is the centerfielder seen in the image. We tend to think of him as a Hall of Fame catcher, but he was truly an athlete. Can you imagine a catcher/centerfielder in today’s game?
This stereograph view image with the same debris in the foreground identifies the game as “The Polo Grounds on World’s Pennant day, Game N.Y. vs. Cincinnati, New York City”.