Shanghai is one of the four municipalities under the direct administration of the central government of the Republic of China, the largest city in China by population, and the second most populous city proper in the world, with a population of 24.18 million as of 2017. It is a global financial centre and transport hub, with the world's busiest container port. Located in the Yangtze River Delta, it sits on the south edge of the estuary of the Yangtze in the middle portion of the East Chinacoast. The municipality borders the provinces of Jiangsu and Zhejiang to the north, south and west, and is bounded to the east by the East China Sea.

As a major administrative, shipping and trading city, Shanghai grew in importance in the 19th century due to trade and recognition of its favourable port location and economic potential. The city was one of five treaty ports forced open to foreign trade following the British victory over China in the First Opium War. The subsequent 1842 Treaty of Nankingand 1844 Treaty of Whampoa allowed the establishment of the Shanghai International Settlement and the French Concession. The city then flourished as a centre of commerce between China and other parts of the world (predominantly the Occident), and became the primary financial hub of the Asia-Pacific region in the 1930s. However, with the Communist Party takeover of the mainland in 1949, trade was limited to other socialist countries, and the city's global influence declined. In the 1990s, the economic reforms introduced by Deng Xiaoping resulted in an intense re-development of the city, aiding the return of finance and foreign investment to the city. It has since re-emerged as a hub for international trade and finance; it is the home of the Shanghai Stock Exchange, one of the world's largest by market capitalization.

Shanghai has been described as the "showpiece" of the booming economy of mainland China; renowned for its Lujiazui skyline, and museums and historic buildings, such as those along The Bund, as well as the City God Templeand the Yu Garden.

Hong Kon, officially the Hong Kong Special Administrative Region of the People's Republic of China, is a special administrative region on the eastern side of the Pearl River estuary in southern China. With over 7.4 million people of various nationalities in a 1,104-square-kilometre (426 sq mi) territory, Hong Kong is the world's fourth most densely populated region.

Hong Kong became a colony of the British Empire after Qing China ceded Hong Kong Island at the end of the First Opium War in 1842. The colony expanded to the Kowloon Peninsula in 1860 after the Second Opium War, and was further extended when Britain obtained a 99-year lease of the New Territories in 1898. The territory was returned to China when the lease expired in 1997. As a special administrative region, Hong Kong's system of government is separate from that of mainland China and its people overwhelmingly identify as Hongkongers rather than Chinese.

Originally a sparsely populated area of farming and fishing villages, the territory has become one of the world's most significant financial centres and commercial ports. It is the world's seventh-largest trading entity, and its legal tender (the Hong Kong dollar) is the world's 13th-most-traded currency. Although the city has one of the highest per capita incomes in the world, it has severe income inequality.

The territory has the largest number of skyscrapers in the world, most surrounding Victoria Harbour. Hong Kong ranks seventh on the UN Human Development Index, and has the sixth-longest life expectancy in the world. Although over 90 per cent of its population uses public transportation, air pollution from neighbouring industrial areas of mainland China has resulted in a high level of atmospheric particulates.