The Damrei Mountains — the Elephant Mountains — had been venerated by Cambodians long before any Frenchman climbed them. What the protectorate saw in the range was altitude, and what altitude offered was relief. Kampot sits thirty-seven kilometres away at the bottom of the slope, on a coast that is oppressive for most of the year; the Bokor plateau is significantly cooler and more humid, fog rolling through it for weeks at a stretch. So in the early 1920s the administration decided to build a town up there for French residents and the soldiers garrisoned in the region, reachable only by a road cut out of jungle and rock.

The centrepiece was the Bokor Palace Hotel, inaugurated in 1925. Around it went the villa of the Résident Supérieur, a post office since demolished, and a small Catholic church. As colonial architecture goes, it is an unusually complete statement of how the occupiers intended to spend their leisure.

The retreat had barely two decades of use before politics took it away. In the late 1940s, with the First Indochina War underway and Khmer Issarak insurgents active in the countryside below, the French pulled off the mountain and left the buildings to the weather.

Independence eventually brought them back. In 1962 the plateau reopened as the Cité du Bokor, and this time the draw was gambling — a casino installed in new hotels near the lake, the Sangkum and the Kiri. An annexe went up beside the palace, along with a mayor's office and a concrete parasol that still stands out on the escarpment like a piece of abandoned stage furniture. King Norodom Sihanouk kept a small summer residence of his own about ten kilometres back down the road, the Black Palace, Damnak Sla Khmao.

The second abandonment came in 1972, when Khmer Rouge forces took the area, and the mountain became something else entirely: ground worth holding. When Vietnamese forces invaded in 1979 and drove the regime from Phnom Penh, the Khmer Rouge dug into the plateau and held on for months. They were still up there in the early 1990s, occupying one of the movement's last redoubts long after the rest of the world had stopped watching.

The end came without a battle. In 1993 a French battalion of the United Nations Transitional Authority in Cambodia moved onto Bokor and established its headquarters inside the old Palace Hotel, and the Khmer Rouge withdrew. Fifteen years later, visitors were still finding bullet strikes in the stonework.

What happened next is the part most visitors actually see. The state owns the site but leased it for ninety-nine years to the Sokimex Group, which announced the project on 19 January 2008: a new road and resort, roughly thirty months of work, about twenty-one million US dollars. The old ascent had been a thirty-two-kilometre grind that took an hour and a half. By December 2011 a sealed road had replaced it, engineered with battered slopes and drainage systems to stop the mountainside sliding into it.

The Thansur Bokor Highland Resort opened the following year, casino included — an idea Bokor had already tried twice. Redevelopment is budgeted at a billion dollars over fifteen years, with a larger Bokor city floated beyond that. Near the summit, a vast statue of Lok Yeay Mao, a revered protective figure in Cambodian folk belief, now looks out over the Gulf.

Most of the original buildings are still standing; the post office is the notable loss. Rangers keep a station on the plateau, a reminder that this ground has never entirely stopped being strategic, and a small temple remains in use. The Popokvil Waterfalls run hard in the wet season and go quiet in the dry. On a clear afternoon the escarpment hands you the whole coastline and the islands out in the Gulf. More often the cloud closes in, and the hotel materialises out of it at fifty metres, grey and enormous and silent.

It is easy to read all this as picturesque ruin, and the crews who shot City of Ghosts here in 2002 and R-Point in 2004 read it exactly that way. But every one of these walls was carried up a mountain by people who were never going to be allowed to stay in them, and nine hundred of whom did not come back down.