The irregular baseline of the White Palace's granite walls seamlessly fuse into the mountain, which contrasts with the geometry of the hundreds of windows and wall tops crowned by dozens of golden roofs.

Within the Red Palace's red walls are the Dalai Lama's bedroom, living room, prayer room, guestroom and study room.

For both religious and practical reasons, visitors must observe several rules.

Hats, sunglasses and bottled water aren't allowed, and cameras can't be taken beyond the White Palace.

Potala only accepts 2,300 visitors a day from 9 am to 12 am, and 3:30 pm to 4:30 pm. Tickets must be booked a day in advance and cost 200 yuan ($33).

Tours of the inner palace start at a stone stairway leading to the compound's back entrance. They are limited to hourlong nonstop walks that pass by all the main sites, such as the scripture halls, and monks' dormitories and tombs.

Only a small section of the palace is open to the public.

The ancient architects paid special attention to the use of the natural light and ventilation through openings in the roofs and walls. All rainfall is collected for residents' daily use.

Virtually every surface is adorned with sculptures, frescos and tapestries. The dancing illumination emanating from butter lamps, the fragrance of incense and the chanting of sutras make the experience multisensory and, ultimately, spiritual.