Where was emperor yong le's imperial city built? why was it known as the forbidden city?

The history of the Forbidden City begins in the 15th century when it was built as the palace of the Ming emperors of China. It is located in the centre of Beijing, China, and was the Chinese imperial palace from the mid-Ming Dynasty to the end of the Qing Dynasty in 1912. It has been a museum since the 1920s.