guangzhou is the capital and the sub-provincial city of guangdong province in the southern part of the people's republic of china. the city is also known by an older english-language name, canton. it is a port on the pearl river, navigable to the south china sea, and is located about 120km north-west of hong kong. as of the xx census, the city has a population of 6 million, and a metropolitan population of 12.6 million,[citation needed] making it the most populous city in the province and the third most populous metropolitan area in china.
with the guangzhou metro, opened in 1999, guangzhou is the fourth city in china to build an underground railway system. currently there are four lines operational with an ambitious plan to expand rapidly with three lines under construction and four lines that are being planned.
guangzhou's main airport is the new baiyun international airport in huadu district, that opened on 5 august xx replacing old baiyun international airport close to the city centre.