Haidian District () is a district of the municipality of Beijing. It is mostly situated in northwestern Beijing, but also to a lesser extent in the west, where it has borders with Xicheng District and Fengtai District. It is 431 square km in area, making it the second-largest district in urban Beijing area (after Chaoyang), and is home to 3,133,469 inhabitants as of November 2020. Sister cities Since 1992, Haidian District has signed official papers and established Sister City relationship with 14 cities and districts from 10 countries of 4 continents. Some sister cities are shown below: South America Santa Fe, Argentina (May 2010) La Falda, Cordoba, Argentina (10 September 2009) North America Cambridge, Massachusetts, United States (8 February 2008) Harrisburg, Pennsylvania, United States (15 April 1998) Europe Savonlinna, Finland (9 March 2016) Olympia, Peloponnesus, Greece (28 February 2008) Groningen, Netherlands (19 October 2004) Bures-sur-Yvette, Massy, Palaiseau, in Paris Region, France (4 October 1994) East Asia Seodaemun-gu, Seoul, South Korea (27 September 1995) Nerima, Tokyo, Japan (13 October 1992) Administrative division The administrative division of the district was reported as follows: 22 subdistricts of the city proper of Beijing 7 towns of which carry the "area" () label: History Haidian was originally a village outside of Beijing's Inner City. It was first built in the Yuan Dynasty and became one of the eight major business areas of the capital during the Qing Dynasty and was the seat of such old shops as Lotus White, Quanjude and Hongbin House. The famed Old Summer Palace and Summer Palace, two grand imperial gardens are also among its reputed features. It became a university district after the building of the Tsinghua University and Yenching University campus in the early twentieth century. It is mentioned in Lao She's novel Camel Xiangzi as an academic village for students. After the foundation of the People's Republic, it was deliberately developed as a university area, with many of the Yan'an institutions moving there. It officially became an administrative district in June 1954. Since the reform and opening up, it has become the centre of China's IT industry. In the words of Time magazine: During the later half of the 1990s, out of the Beijing districts, Haidian had the highest per capita GDP. During that period the GDP of Haidian (1) District grew by double digits each year. Transportation The northwestern stretches of the 3rd Ring Road, 4th Ring