By Rupert Wingfield-Hayes BBC News, Beijing
The completion of the Tibet railway is being hailed in China as one of the world's great engineering marvels.
The longest high-altitude railway in the world, it will ease access to the remote region. Test runs are due to begin on 1 July.
Tibet's extraordinary isolation has kept it poor. Education levels and life expectancy fall well behind the rest of China. But that isolation has also helped to preserve Tibet's unique culture and way of life.
The arrival of the railway will bring tremendous change. China's communist rulers say it will open up Tibet, bringing greater prosperity for its entire people. Detractors say the opening of the railway is the death knell of an independent Tibetan culture.
It doesn't feel like our home any more
Sedeng Tibetan shop owner
Before the railway there were only two ways into Lhasa: an expensive plane ride, followed by a hair-raising touch down; or three days and nights on an overcrowded bus bouncing along back-breaking mountain roads.
Many a bus, and its passengers, has ended up crushed at the bottom of a lonely ravine.
Along the route of the railway, opinions vary about whether it is good or bad. While visiting a remote construction site on my most recent trip to Tibet I came across two Tibetan herders lounging beside the road. They were sitting on top of huge bundles of yak wool.