Purple Mountain Observatory and Tianwen Peak Trail

The Purple Mountain Observatory and Tianwen Peak Trail climbs through forest on the western part of Zijin Shan in Xuanwu District, Nanjing, Jiangsu Province, China, to the historic Purple Mountain Observatory. The observatory, founded in the early twentieth century, is one of China's best-known astronomical institutions, and its domes and buildings sit on the mountain's Tianwen Peak, whose name means astronomy. Access is by metro and taxi: Metro Line 2 to Muxuyuan or Line 4 to Zhongshan Ling gets visitors to the city side of the mountain, and a taxi is then needed to reach the lower observatory road, since public bus service on the mountain roads is limited. Parking is possible near the lower road for those driving. No separate hiking permit is known for the trail, though visitors should follow signage at the observatory grounds, where some areas are working research facilities and are not open to walk into. The out-and-back route is about 6 km and involves roughly 250 m of cumulative gain, taking 2.5 to 3.5 hours. It is graded moderate because the ascent is continuous rather than because of technical terrain. The surface is mainly stone steps and paved or packed paths through mixed broadleaf and conifer woodland, which gives dense shade for most of the climb and makes summer walking tolerable, though mosquitoes are common from June to September. Exposure is minimal, with fenced sections near viewpoints. Landmarks include the forested lower slopes, small pavilions used as rest points, the observatory buildings with their historic instruments and the summit outlook, from which Xuanwu Lake and the city can be seen in clear conditions. The natural turn-around is the observatory itself; there is no need to continue beyond it. Water is not reliably sold along the trail, so about one litre per person should be carried. There are no refuge huts, though pavilions and the observatory's grounds give shelter from brief showers. Hikers should plan to finish before dusk, since the woodland becomes dark early and lighting on the steps is limited.