I'm surprised this wasn't added sooner. Very cool!
FYI: "The original Polo Grounds was built in the 1870s for the sport of polo, thus accounting for its name. The field was originally referred to in newspapers simply as the polo grounds, and over time the designation became a proper name. It was converted to a baseball stadium when leased by the New York Metropolitans in 1880. The stadium was used jointly by the Giants and Metropolitans from 1883 until 1885, and the name stuck for each subsequent stadium of the Giants. The fourth and final Polo Grounds, which the Giants used until they moved to San Francisco after the 1957 season, and which the Mets used until Shea Stadium was completed in 1964, was the most famous, and the one most people mean when they refer to the Polo Grounds. It hosted many events over the years, though never an actual polo match."
Residential 
FYI: "The original Polo Grounds was built in the 1870s for the sport of polo, thus accounting for its name. The field was originally referred to in newspapers simply as the polo grounds, and over time the designation became a proper name. It was converted to a baseball stadium when leased by the New York Metropolitans in 1880. The stadium was used jointly by the Giants and Metropolitans from 1883 until 1885, and the name stuck for each subsequent stadium of the Giants. The fourth and final Polo Grounds, which the Giants used until they moved to San Francisco after the 1957 season, and which the Mets used until Shea Stadium was completed in 1964, was the most famous, and the one most people mean when they refer to the Polo Grounds. It hosted many events over the years, though never an actual polo match."
That's from & there's much more info at:
http://en.wikipedia.org/wiki/Polo_Grounds