The Potala is administered as a museum by a government whose authority over Tibet is the central dispute, on behalf of an institution now in exile. Everything about the site follows from that.
What it was
Songtsen Gampo is traditionally credited with a palace on Marpo Ri, the Red Hill, in the seventh century.
The present building was begun on the order of the fifth Dalai Lama in 1645. The government moved into the White Palace in 1649. The Red Palace was added between 1690 and 1694, completed some twelve years after the fifth Dalai Lama's death, which his regent Desi Sangye Gyatso concealed in order to keep the work and the government going. An entire state was administered in the name of a man known by a few to be dead.
Thirteen storeys, over a thousand rooms, at about three thousand seven hundred metres. The White Palace held the administration; the Red Palace holds chapels and the funerary stupas of eight Dalai Lamas, the fifth's sheathed in several tonnes of gold.
It is Gelug in tradition, and it was the seat of the Tibetan government until 1959.
1959
Chinese shells struck the palace during the Lhasa uprising of March 1959. The fourteenth Dalai Lama fled to India during that rising and has never returned.
The building escaped the worst of the Cultural Revolution largely through Zhou Enlai's personal intervention, a fact usually cited to the credit of the individual rather than the policy, since the Jokhang a short distance away was not spared.
What it is now
A state-administered museum. Timed tickets, a daily visitor quota of roughly two thousand three hundred, fixed routes, restricted photography, and guides working to an approved account.
UNESCO inscribed it in 1994.
The thing that cannot be described neutrally
Every fact above is uncontested. What they add up to is not.
One account: a fragile high-altitude monument, protected by the state, restored at public expense, opened to visitors under sensible conservation limits.
Another: the empty seat of a government in exile, held by the power that displaced it, presented to ticket-holders as heritage rather than as a functioning institution, with the person whose residence it is unable to enter.
Both descriptions fit the same building. This entry does not choose between them, and a reader should be suspicious of any account of the Potala that does so without noticing it has.