The imperial palace complex at the centre of Beijing, home to the Ming and Qing dynasty emperors from 1420 until the end of imperial China in 1912. A walled rectangle of 72 hectares and nearly a thousand surviving buildings, it is the largest preserved wooden palace complex in the world and the single best place to understand imperial China.
A full visit is a day, walking north to south through the Meridian Gate, across the ceremonial courtyards, and into the inner court where the emperor and his family actually lived. Tickets sell out online in peak season; book ahead on the official site and bring your passport. Entry is from the south; you can't re-enter once you've left.