Fairmount Park is the Goliath of urban parks. The entire system, which includes 63 parks, clocks in at 9,200 acres, making it the largest urban park in the nation. Seriously: It's five times bigger than NYC's Central Park. To show off its size, the website SpareFoot Blog superimposed an outline of the actual park onto a bunch of city maps, including San Francisco, Chicago, and Boston. (Note: The actual park is 4,200 acres, which is the size they used for the maps.)
You can find more Fairmount Park comparisons here, or make your own maps.
· How Big is Philadelphia's Fairmount Park, Actually? [Sparefoot Blog]