Winnipeg is the capital of Manitoba. Its heart is the Forks, a historic site at the intersection of the Red and Assiniboine rivers, with warehouses converted to shops and restaurants, and ample green space dedicated to festivals, concerts and exhibits. Nearby, the Exchange District is known for its well-preserved turn-of-the-10th-century architecture and numerous art galleries. The city population as calculated in 2011 was 663,617. The population of the Metropolitan district in total is 730,000. Winnipeg developed from fur trading posts. Summers are warm and humid with frequent thunderstorms, winters are very cold and dry, and spring and fall are temperate. Various residential neighbourhoods surround downtown in all directions; expansion is greatest to the south and west, although several areas remain underdeveloped. The largest park in the city, Assiniboine Park, houses the Assiniboine Park Zoo and the Leo Mol Sculpture Garden. As of 2011, there are 16 National Historic Sites of Canada in Winnipeg. One of these, The Forks, attracts four million visitors a year.