'The Emperor's Private Paradise: Treasures From the Forbidden City" is not so much a show as an experience. Its subject is a 1.5-acre garden complex inside the Tranquility and Longevity Palace, a compound that the fifth Qing Emperor, Qianlong, built in the 1770s in the northwest corner of Beijing's Forbidden City. On display are about 90 such works from the Forbidden City's Palace Museum, which since 2001 has been collaborating with the World Monuments Fund to restore and conserve the Qianlong Garden. The restoration is slated for completion in 2019.