Brooklyn (Kings County), on the western tip of Long Island, is the city's most populous borough. Brooklyn is known for its cultural, social, and ethnic diversity, an independent art scene, distinct neighborhoods, and a distinctive architectural heritage. Downtown Brooklyn is the largest central core neighborhood in the outer boroughs. The borough has a long beachfront shoreline including Coney Island, established in the 1870s as one of the earliest amusement grounds in the country.[18] Marine Park[19] and Prospect Park are the two largest parks in Brooklyn. Since 2010, Brooklyn has evolved into a thriving hub of entrepreneurship and high technology startup firms,[20][21] and of postmodern art[22] and design.[21] Queens (Queens County), on Long Island north and east of Brooklyn, is geographically the largest borough, the most ethnically diverse county in the United States,[23] as well as the most ethnically diverse urban area in the world.[8][9] Historically a collection of small towns and villages founded by the Dutch, the borough has since developed both commercial and residential prominence. Downtown Flushing has become one of the busiest central core neighborhoods in the outer boroughs. Queens is the site of Citi Field, the baseball stadium of the New York Mets, and hosts the annual U.S. Open tennis tournament at Flushing Meadows-Corona Park. The borough is also home to the largest public housing development in the Western Hemisphere, Queensbridge. Additionally, two of the three busiest airports serving the New York metropolitan area, John F. Kennedy International Airport and LaGuardia Airport, are located in Queens. (The third is Newark Liberty International Airport in Newark, New Jersey.) The Bronx (Bronx County) is New York City's northernmost borough and the only New York City borough that is part of the United States mainland. It is the location of Yankee Stadium, the baseball stadium of the New York Yankees, and home to the largest cooperatively owned housing complex in the United States, Co-op City.[24] It is also home to the Bronx Zoo, the world's largest metropolitan zoo,[25] which covers 265 acres (107ha) and houses over 6,000 animals.[26] Directly to the zoo's north is the New York Botanical Garden, a botanical garden and National Historic Landmark. Pelham Bay Park is the largest park in New York City, at 2,772 acres (1,122ha).[19] Staten Island (Richmond County) is the most suburban in character of the five boroughs. Staten Island is connected to Brooklyn by the Verrazzano-Narrows Bridge and to Manhattan by way of the Staten Island Ferry, a free commuter ferry and popular tourist attraction which provides unobstructed views of the Statue of Liberty, Ellis Island, and Lower Manhattan. In central Staten Island, the Staten Island Greenbelt spans approximately 2,500 acres (10km2), including 28 miles (45km) of walking trails and one of the last undisturbed forests in the city.[27] Designated in 1984 to protect the island's natural lands, the Greenbelt comprises seven city parks.