Purple Mountain Observatory

China's first modern observatory, completed in 1934 on the third peak of Purple Mountain, hailed as "the cradle of modern Chinese astronomy"; today a science-outreach observing station and a museum on its historic site. Its most precious holdings are ancient astronomical instruments replicated during the Ming and Qing dynasties—the armillary sphere (hunyi), simplified armilla (jianyi) and celestial globe (tiantiyi) among them—whose originals were copied in the Ming Zhengtong reign from the Yuan astronomer Guo Shoujing's instruments; national-treasure-level astronomical artifacts that fix a thousand years of Chinese sky-watching onto the mountaintop platform. To go up, take the cable car to mid-mountain and walk the rest; the vantage over Nanjing city and Xuanwu Lake is superb, and astronomy fans and families with kids especially shouldn't miss it.

Getting there: Purple Mountain, by cable car / on foot