"Capital of Red China" is a popular phrase that refers to the capital city of the People's Republic of China - Beijing. However, there are other synonymous terms that can be used to refer to this city. Some of the synonyms include "Imperial Capital," "Northern Capital," "City of Emperors," and "Peking." These names have roots in Chinese history and culture, and are often used interchangeably with Beijing. Peking, for instance, is the old form of the city's name and is still commonly used in some areas. Overall, these synonyms help to provide a better understanding of the capital city of China and its rich place in history and culture.