Upper Mustang is among the most spectacular and culturally preserved regions accessible to trekkers in the Himalayas. Until 1992 it was a restricted kingdom, and it still requires a special permit — US$500 for ten days — that keeps visitor numbers low and the trails uncrowded. The landscape is nothing like the rest of Nepal: an eroded red and ochre canyon country of crumbling cliffs, cave dwellings, and ancient monasteries that looks more like the American Southwest than the Himalayas.
The main destination is Lo Mantang (3,840m), the walled capital of the former Lo Kingdom, a day's walk north of Kagbeni. The town's white-walled buildings, four-storey palace, and Jampa Lhakhang monastery have changed little in five centuries. The gompa contains 15th-century wall paintings and large clay statues in excellent condition. Monks still conduct daily prayers here; the monastery is active, not a museum.
The trek to Lo Mantang takes four to five days from Jomsom, through a succession of extraordinary villages — Chele, Syangboche, Ghemi, Charang — each with its own ancient gompa and eroded landscape. The return trip can be varied by taking a different route. The permit cost funds conservation and keeps the area from being overrun; the experience of walking in a Tibetan Buddhist kingdom that the modern world largely bypassed is worth every rupee.