The Gyantse Dzong is a commanding 14th-century fortress perched on a great spur of grey-brown rock above the town. It is one of the best-preserved dzongs (fortress-palaces) in all of Tibet, and from the top, on a clear day, you can see across the barley fields to the monastery walls and, if lucky, glimpse the snowy peaks of the Himalayas to the south.
The dzong contains a small Anti-British Imperialist Museum commemorating the 1904 Younghusband expedition — an episode that the Chinese government frames as colonial aggression, and that the exhibits treat with considerable indignation. The museum is interesting less for balance than for the singular perspective it provides on a genuine historical trauma.
The climb to the dzong is steep but short — about 20 minutes from the base. The views from the top are worth the effort even if the museum is not your thing. Go in the late afternoon for the best light on the monastery complex below.