This is called the Palace Museum, and was built and used as a Palace by the Ming and the Qing Dynasties. This place is easy to find as it is just on the center of the city and most public transports will take you there. This was the palace of the Chinese Emperors and is now a cultural center of the government. The attractions to see here, among others are the Hall of Supreme Harmony, Hall of Preserving Harmony and Hall of Middle Harmony. This is now a UNESCO heritage site. It is close to Tiananmen Square and the timing is 8:30 AM to 4:20 PM from October 16 to Apr 15and from 8:30 AM to 5 PM during April 16 to October 15.
See also : See the valor at Tiananmen Square