Guangzhou (also known as Canton, and less commonly as Kwangchow) is the capital and largest city of Guangdong province in South China. Located on the Pearl River, about 120 km (75 mi) north-northwest of Hong Kong and 145 km (90 mi) north of Macau, Guangzhou serves as an important national transportation hub and trading port. One of the five National Central Cities, it holds sub-provincial administrative status.Guangzhou is the third largest Chinese city and the largest city in South Central China. In 2014 the city's administrative area was estimated to have a population of 13,080,500. Some estimates place the population of the entire Pearl River Delta Mega City built-up area as high as 44 million including Guangzhou's nine urban districts, and Shenzhen (10.36 million), Dongguan (8.22 million), Zhongshan (3.12 million), most parts of Foshan (7.20 million), Jiangmen (1.82 million), Zhuhai (0.89 million) and Huyang County of Huizhou (0.76 million) adjoining Dongguan and Shenzhen, with an area of about 17,573 square kilometres (6,785 sq mi). Guangzhou is part of one of the most populous metropolitan agglomerations on Earth. The total population of this agglomeration is over 54 million, including the population of adjacent city Hong Kong. Guangzhou is identified as a Beta+ world city.