Shanghai (Putonghua pronunciation: ) is one of the four municipalities of the People's Republic of China. It is located on the southern estuary of the Yangtze, with the Huangpu River flowing through it. With a population of 24.2 million it is the most populous urban area in China and the second most populous city proper in the world. Shanghai is a global center for finance, innovation, and transportation, and the Port of Shanghai is the world's busiest container port. Originally a fishing village and market town, Shanghai grew in importance in the 19th century due to trade and its favorable port location. The city was one of five treaty ports forced open to foreign trade after the First Opium War. The Shanghai International Settlement and the French Concession were subsequently established. The city then flourished, becoming a primary commercial and financial hub of the Asia-Pacific region in the 1930s. During the Second Sino-Japanese War, the city was the site of the major Battle of Shanghai. After the war, with the CPC takeover of mainland China in 1949, trade was limited to other socialist countries, and the city's global influence declined. In the 1990s, economic reforms introduced by Deng Xiaoping resulted in an intense redevelopment of the city, especially the Pudong district, aiding the return of finance and foreign investment to the city. The city has since re-emerged as a hub for international trade and finance; it is the home of the Shanghai Stock Exchange, one of the largest stock exchanges in the world by market capitalization, and the Shanghai Free-Trade Zone, the first free-trade zone in China. Shanghai has been described as the "showpiece" of the booming economy of China. Featuring several architecture styles such as Art Deco and shikumen, the city is renowned for its Lujiazui skyline, museums, and historic buildings—including the City God Temple, Yu Garden, the China Pavilion, and buildings along the Bund. Shanghai is also known for its sugary cuisine, distinctive dialect, and vibrant international flair. Every year, the city hosts numerous national and international events, including Shanghai Fashion Week, the Chinese Grand Prix, and ChinaJoy.