Beijing (北京 Běijīng) is the capital of the People's Republic of China, the most populous country in the world. Beijing literally means Northern Capital, a role it has played many times in China's long history. From 1264 Beijing served as the capital of a united China under Kublai Khan. His victorious Mongol forces renamed the city, Great Capital (大都). In 1403 the 3rd Ming Emperor, Zhu Di, also known as Emperor Yongle, moved the capital back to Beijing and gave the city its present name. The Ming period was Beijing's golden era. The Forbidden City, the Temple of Heaven and many other Beijing landmarks were built in this period. The capital developed into a huge city becoming the religious and cultural center of Asia. In 1644, the Manchus overthrew the declining Ming dynasty and established China's last imperial line - the Qing. Beijing remained the capital. The Qing dynasty fell in 1911 and The Republic of China was established, then Beijing was renamed as Beiping. When the Kuomintang was defeated by the Communists in 1949, the new government proclaimed a People's Republic with its capital at Beijing.
Beijing is an important world capital, and one of the world's leading centers for politics, economy and business, finance, education, culture, innovation and technology, architecture, language, and diplomacy. A megacity, Beijing is the second largest Chinese city by urban population after Shanghai and is the nation's political, cultural, and educational center. It is home to the headquarters of most of China's largest state-owned companies and houses the largest number of Fortune Global 500 companies in the world, as well as the world's four biggest financial institutions. It is also a major hub for the national highway, expressway, railway, and high-speed rail networks. The Beijing Capital International Airport has been the second busiest in the world by passenger traffic since 2010, and, as of 2016, the city's subway network is the busiest and second longest in the world.
Combining both modern and traditional architecture, Beijing is one of the oldest cities in the world, with a rich history dating back three millennia. As the last of the Four Great Ancient Capitals of China, Beijing has been the political center of the country for most of the past eight centuries, and was the largest city in the world by population for much of the second millennium A.D. Encyclopaedia Britannica notes that "few cities in the world have served for so long as the political headquarters and cultural center of an area as immense as China." With mountains surrounding the inland city on three sides, in addition to the old inner and outer city walls, Beijing was strategically poised and developed to be the residence of the emperor and thus was the perfect location for the imperial capital. The city is renowned for its opulent palaces, temples, parks, gardens, tombs, walls and gates. It has seven UNESCO World Heritage Sites—the Forbidden City, Temple of Heaven, Summer Palace, Ming Tombs, Zhoukoudian, and parts of the Great Wall and the Grand Canal— all tourist locations. Siheyuans, the city's traditional housing style, and hutongs, the narrow alleys between siheyuans, are major tourist attractions and are common in urban Beijing.