Xi 'an, referred to as "Gao", was called Chang 'an and Haojing in ancient times. It is the capital of Shaanxi Province, a sub-provincial city, a megacity and the core city of Guanzhong Plain urban agglomeration. It is an important central city in western China and an important national scientific research, education and industrial base approved by the State Council. As of 20 19, the whole city has two counties1/district, with a total area of 10752 square kilometers, a built-up area of 7006.9 square kilometers, a permanent population of 10203500 and an urban population of 761.