Kep now attracts Cambodian tourists in great number, who go to splash about in the soupy Gulf of Thailand, eat fresh seafood on little wooden platforms set up by the sea and visit former king Norodom Sihanouk's bizarre palace on a headland overlooking the town.

The 1960s-style villa, one of several built in southern Cambodia by Sihanouk, was never occupied by the king, although it is still furnished as if awaiting his arrival. Its main purpose now is as a viewpoint over the pretty half-moon bay and a reminder of Sihanouk's profligacy.

Bokor hill station is now part of the Preah Monivong Bokor National Park. Reaching it remains an arduous affair best tackled in a four-wheel-drive or a sturdy pick-up truck. Drivers wait at the base of the mountain at the entrance to the national park, scouting for travellers who have decided that riding pillion on a Chinese Honda Dream knock-off is too daunting.

The route twists and turns for 90 minutes before reaching the top of the Elephant Hills; it is far more sensible to measure travel in Cambodia in time rather than kilometres. The track is in dreadful condition, even for a country that specialises in appalling roads.

I sit bouncing in the back of a Toyota pick-up, uneasily propped on a couple of cushions with my legs braced against the vehicle's side and my arms straining against the roll bar to try to stop myself cracking my head on it. The driver has told me the ride inside the cabin is even rougher, which I doubt, but he convinced me to perch outside by pointing out the air-conditioning has to be switched off. The cool air Bokor promises will surely flow better in the open rear of the vehicle than directly behind a straining engine.

Bokor is 1,080 metres above sea level and is always considerably cooler than the coast. As we wind up the hill under a rainforest canopy that screens the worst of the sun's rays, the air seems fresher by the minute. When the forest thins and the road levels out, we are on a grassy plain strewn with boulders and largely devoid of trees. Soon, we come to the Black Palace.

The palace is another of Sihanouk's follies. It was built in 1964 but is now a concrete shell through which the wind whistles eerily. It has a few rooms and a semi-circular terrace with a staggering view of the coast, the Vietnamese island of Phu Quoc and the bold summit of Bokor. All the windows are broken and graffiti is scored into the rusty red lichen that clings to the walls.

A few kilometres farther stands Bokor hill station proper. The decision to build it was made in 1917 and by 1921, the road to it was finished. It was another three years before the resort's two main structures, the Bokor Palace Hotel and the Catholic church, were completed. The church lies just off the road, behind a lone tree, a strangely displaced French provincial building with a dark past. During the civil war that followed the ousting of Pol Pot's brutal Khmer Rouge regime in 1979, it was used as a refuge by remnant Khmer Rouge fighters. The hotel, meanwhile, housed Vietnamese and Cambodian loyalist forces. Shells and bullets were traded back and forth between the two buildings.

Inside the church, amid the graffiti - Dara, a guide from Kampot, has waxed lyrical: 'A woman without husband is like a night without moon' - there is a drawing of a Khmer Rouge soldier, said to be a self-portrait. The exterior is largely untouched, save for the pockmarks of war, and inside, the stone altar and a kitchen at the rear are intact. But the tiled floor is broken and there is a gaping hole in the bell tower.

The hotel once incorporated a casino and the gaming room was a splendid example of colonial grandeur - 30 metres square with a high ceiling, pillars and panoramic windows. Beyond it, again overlooking the coast, was a wide terrace, and above that, a series of balconies from which it is said many a failed gambler leaped to his death.

Within a few years of its opening, a visit to the Bokor Palace Hotel had become a popular excursion for travellers on the Bangkok-Saigon steamer. When it berthed at Ream, south of the tip of the Elephant Range near modern-day Sihanoukville, passengers would disembark into motor coaches for the long trip up the hill.

The hotel's name is still faintly visible above the entrance and many of the richly ornamented tiles that covered the floor are still intact. Most of the windows and shutters in the 95 rooms are smashed, the immense carved wooden door to the gaming room is rotten and the walls inside and out are clad with more red lichen, which grows on all of Bokor's buildings and on the rocks scattered about the plain.

Signs in English and Khmer read, 'Do not sleep here', but there is little chance of today's few travellers wishing to spend a night in this sinister place, with its rattling shutters, dense mists and lonely ghosts.

Bokor hill station was abandoned twice before 1979 - first in the 40s, when it was overrun by Vietnamese and Free Khmer forces fighting the French colonial administration, and again in 1970, when the embattled Lon Nol regime left it to the Khmer Rouge.

The Khmer Rouge also took over the former French commandant's house and other colonial villas. The two-storey commandant's house still contains a table made from an ammunition box used by the Khmer Rouge. These buildings are as broken and foreboding as the others on the hill, with cobwebs, collapsing ceilings and rubble-filled staircases. One villa houses a smashed frieze of ancient Cham Muslim soldiers marching to war.

Not surprisingly, some international hotel companies have expressed interest in redeveloping Bokor hill station, particularly the hotel, but conservationists would like to see this time capsule of 20th-century colonial Indochina and civil war remain as an atmospheric monument to an extraordinary period of Cambodian history. A five-star casino-hotel, spa and golf course at such an evocative site? Now that would really be the ruin of Bokor.