An important Chinese administrative centre and army base, Tsetang (Zédāng) is the fourth-largest city in Tibet and the capital of huge Shānnán (Lhoka) prefecture. The centre of town is a modern, thoroughly Chinese city where you’ll find decent restaurants, midrange accommodation and a couple of internet cafes. The more interesting area is the small traditional Tibetan town, clustered to the east around Gangpo Ri, one of Ü’s four sacred mountains.
Most travellers use Tsetang as a base to visit outlying sites of the Yarlung Valley. The PSB has a strong presence here so your guide will probably disappear for a few minutes to register your passport and pick up an alien's travel permit for outlying sights (including Samye Monastery).