So here we are, after spending a crazy amount of time around Tiananmen Square, finally through the wall and into the Forbidden City, off limits to commoners for centuries Wikipedia has a wealth of information if you're interested. Briefly, the Forbidden City is about 180 acres of Halls and Palaces. It housed 24 emperors for about 500 years starting with the Ming Dynasty in 1420.
Since 1925, the Forbidden City has been under the charge of the Palace Museum, whose extensive collection of artwork and artefacts were built upon the imperial collections of the Ming and Qing dynasties.