The air grows thin at 3,656 metres. Every staircase calls for a pause, every climb sets its own pace, and that is how Lhasa welcomes its visitors: by making them slow down. No ship will ever approach the capital of Tibet, and this guide is for travellers considering extending an Asian cruise with an overland extension to one of the world's great spiritual centres.

An Extension That Takes Planning

Lhasa can't be improvised. Foreign travellers must visit as part of an organized tour, with a guide and a Tibet entry permit obtained in advance through an authorized agency. Access is by plane from major Chinese cities or by the train that crosses the high plateaus. Once there, the golden rule comes down to one word: acclimatization. Reputable tours plan a first day without exertion, giving the body time to adjust to the altitude; drinking plenty of water and getting enough sleep are part of the program just as much as the monuments.

The Potala, a Man-Made Mountain

Nothing truly prepares you for your first sight of the Potala Palace. Founded in the seventh century and rebuilt in the seventeenth, the former seat of the Dalai Lamas tiers its white and ochre walls across an entire hill: thirteen levels of chapels, golden tombs and stairways that seem to climb into the sky. The visit proceeds in slow stages, amid the smell of the yak butter that fuels the votive lamps. Quotas limit the number of daily entries: your tour will reserve the tickets, and the assigned time will structure your day.

The Jokhang and the Barkhor Circuit

In the heart of the old town, the Jokhang Temple, also founded in the seventh century, remains the most sacred sanctuary of Tibetan Buddhism. Its architecture blends Tibetan, Chinese, Nepalese and Indian influences, and pilgrims prostrate themselves full length before its doors, in a continuous movement whose silent fervour is deeply impressive. All around, Barkhor Street forms a devotional circuit that the faithful walk clockwise, prayer wheels in hand. Joining in, at the pace of pilgrims from all over the plateau, remains for many the most powerful memory of the trip.

The Great Monasteries

On the outskirts of the city, the Sera and Drepung monasteries complete the picture. Drepung was in its day one of the largest monastic centres in the world, a true religious city tiered at the foot of the mountains; Sera remains known for its monks' philosophical debates, contests punctuated by hand claps in a shaded courtyard, which visitors watch in silence. Tours generally devote half a day to each, leaving time to take in the places without rushing.

Pointers for Your Plans

• Plan at least three to four days on site to adjust to the altitude and see the main sites.
• Permit and guide mandatory for foreign visitors: everything goes through a specialized agency.
• People with heart or respiratory conditions should consult their doctor before committing.
• Conditions for entering Tibet change; your travel advisor will confirm feasibility at the time of booking.
• Bring warm clothing in every season: evenings stay cool on the high plateaus, even in summer.

You don't come back from Lhasa as you would from an ordinary capital. The harsh light of the plateau, the prayer flags snapping in the wind and the patience of the pilgrims stay with those who make the detour for a long time. For long-haul travellers, adding the roof of the world to a maritime itinerary means joining the two extremes of geography in a single journey: sea level and the gates of the Himalayas.