Xi'an (UK: shee-AN, US: shee-AHN; Chinese: [ɕí.án] (listen)), also known as Sian, is the capital of Shaanxi Province. A sub-provincial city on the Guanzhong Plain in Northwest China, it is one of the oldest cities in China, the oldest prefecture capital and one of the Chinese Four Great Ancient Capitals, having held the position under several of the most important dynasties in Chinese history, including Western Zhou, Qin, Western Han, Sui, Northern Zhou and Tang. The city is the starting point of the Silk Road and home to the UNESCO World Heritage set Terracotta Army of Emperor Qin Shi Huang.Since the 1980s, as part of the economic growth of inland China especially for the central and northwest regions, Xian has re-emerged as a cultural, industrial, political and educational centre of the entire central-northwest region, with many facilities for research and development, national security and space exploration. Xian currently holds sub-provincial status, administering 11 districts and 2 counties. The city is the third most populous city in Western China, the other two being Chongqing and Chengdu, as well as the most populous city in Northwestern China. In 2020, Xi'an was ranked as Beta- from the GAWC biannual city rankings, and, according to the country's own ranking, ranked 17th.Xi'an is also one of the top 40 science cities in the world by scientific research output as tracked by the Nature Index, and home to multiple China's prestige universities, including Xi'an Jiaotong University, Northwestern Polytechnical University, Chang'an University, Xidian University, Shaanxi Normal University and Northwest University.