Guangzhou - also known as Canton or Kwangchow, is a sub-provincial city and the capital of the Guangdong province in the People's Republic of China. It is one of the five National Central Cities. Located in southern China on the Pearl River, about 120 km (75 mi) northwest of Hong Kong, Guangzhou is a key transportation hub and trading port. It is the third largest city in China and southern China's largest city. Being the city opened to the world earliest in China, Guangzhou is one of the modernist cities in China. It is also a city named Flower city. Each year, there will be a flower exhibition and people from all over the world coming to Guangzhou to join this event.