Interestingly, Hong Kong and Macau are rarely referred to as "cities" in Chinese and their official names don't include the character for city, 市. But whilst they are not officially named as such, I think you would agree with me that Hong Kong and Macau can both be considered to be cities. Indeed Hong Kong even promotes itself to the world as being "Asia's World City". Under China's "One Country, Two Systems" model, the cities of Hong Kong and Macau enjoy the highest level of autonomy from Beijing. Both have their own legal systems and companies registered in Hong Kong and Macau operate in a different jurisdiction to those in Mainland China.