when was this monument built?
From 1406 to 1420 it was constructed
Forbidden City
 from 1406 to 1420
the forbidden city of ming and qing dynasties UNANSWERABLE what is the "forbidden city"? It is a palace complex where is it located? Dongcheng District, Beijing, China
wiki:13421420
Forbidden City [SEP] Introduction
Today, the Forbidden City houses the Palace Museum, and was the former Chinese imperial palace and winter residence of the Emperor of China from the Ming dynasty (since the Yongle Emperor) to the end of the Qing dynasty, between 1420 and 1924. The Forbidden City served as the home of Chinese emperors and their households and was the ceremonial and political center of the Chinese government for almost 500 years. Constructed from 1406 to 1420, the complex consists of 980 buildings, reportedly encompassing 9,999 rooms and covering 72 hectares (over 180 acres). The palace exemplifies the opulence of the residences of the Chinese emperor and the traditional Chinese palatial architecture, and has influenced cultural and architectural developments in East Asia and elsewhere.