The Polo Grounds is one of baseball's most sacred ballparks. Built below Coogan's Bluff in 1891, the bathtub-shaped stadium played host to iconic baseball moments, including Willie Mays's famous catch in the 1954 World Series and Bobby Thomson's "shot heard "round the world." The era before those moments holds a history all its own, when the New York Giants, Yankees, and the football Giants shared the park. The dawn of the 20th century through the 1920s is a rarely seen chapter in Polo Grounds history, and it is presented here for the first time in all of its photographic glory.