SIEM REAP, Cambodia — Angkor Wat’s magnificence has endured nature, invading armies, artifact bandits and occupation by Khmer Rogue communist guerillas.

But nearly a millennium after the 12th-century temple’s creation, it faces its greatest threat yet: millions of tourists marching upon its stones and pawing at its intricate stonework with greasy hands.

Tourism is exploding at Angkor Wat, a world of sandstone ruins considered mankind’s largest pre-industrial city. Jungled over for centuries, and more recently unreachable during Cambodia’s decades of war, the site now absorbs more than a million visitors each year.

But while preservationists cringe at the site’s commercial takeover, they might as well brace for more. The Disneyfication is just beginning.

“See that?” said Hyo-Soon Park, a South Korean developer, standing on a balcony outside his office in Cambodia. “You can see Angkor Wat from here.”

The temple’s tallest tower was visible, in the distance, as a finger of sandstone jutting above the tree line. “When all this is finished, guests will be able to stare at it from their hotel rooms,” Park said. “They’re going to love it.”

Park’s project, called “AngkorCoex,” is a 400-acre temple-themed sprawl of golf courses, hotel suites, duty-free shopping and a large convention center. Site plans also call for a wellness center and something described as a “Bohemian Island with Innovative Playground.” Completion is expected in a year or two.

“The point is this: how can we catch tourists, keep them in one place, here, where they spend all their money?” Park said.

After its long tourism twilight, Cambodia now expects 2.8 million arrivals throughout 2011. That’s double the number of arrivals in 2005 and it’s nearly 25 times more than the paltry 118,000 who visited in 1993.

Tour groups from Asia’s rising economies — not starry-eyed, dreadlocked thrill-seekers — are doing the most to drive Cambodia’s tourism figures up. Chinese tourists, according to Cambodia’s tourism ministry, have increased by 29 percent within the past year. Asian travelers are the demographic targeted by AngkorCoex, Park said.

The majority of those tourists will want to set foot inside Angkor Wat. But conservationists say the temples are suffering serious damage from all that traffic.

“You have to think of it like the Mona Lisa,” said Jeff Morgan, director of the Global Heritage Fund, a U.S.-based organization devoted to preserving historical sites in the developing world.

“If everybody goes and touches the Mona Lisa, it’s going to be worn out. That’s what is happening at Angkor,” he said. “You have millions of people climbing all over these sites.”

The temple was popularized in the West by a French naturist, Henri Mahout, who hacked through dense bramble to find the temples covered in vines. He later wrote that they were “grander than anything left to us by Greece or Rome ... a sad contrast to the state of barbarism in which the nation is now plunged.”

That was 150 years ago. Today, a visit to Angkor Wat can resemble a Saturday at Six Flags. Visitors spill out of tour buses by the thousands, a noisy throng stampeding over stonework laid by servants of the long-dead King Suryavarman II.

All those sneakers wearing away priceless stone is unacceptable, Morgan said. His organization has advocated simple safeguards: wooden walkways, a per-day limitation on visitors and guards to stop tourists from scampering up temples.

“It’s not just tourists,” Morgan said. “It’s what the government does to cater to tourists.”

Edifices are sometimes restored with concrete and rebar, which causes “irreversible damage,” Morgan said. “They’re basing it off some sketches from a French exhibition in 1930. It’s unscientific,” he said.

A Global Heritage Fund team conserving a smaller temple called Bantaey Chhmar has vowed not to repeat the mistakes made at Angkor Wat.

Damage to Angkor Wat is especially disconcerting given its profound significance to Cambodians, said Sotheara Vong, a Khmer historian with the Royal University of Phnom Penh.

The ruins are a sorely needed source of pride for a country still healing from centuries of foreign invasion, French colonial dominance and warfare. “It’s our historical magnet of consolidation and national pride,” Sotheara said. “It’s our identity.”

But for now, Cambodia’s tourism authorities show little willingness to stem the tide of tourists paying to enter Angkor Wat. And as foreign conservationists stream in to preserve the temples, so do foreign developers with new plans to capitalize on the tourism gold rush.

“This here, it’s going to be a square for Cambodian artists,” said Park, gesturing to point on his wall-sized master plan for AngkorCoex.

“The artists can show guests how to make ancient crafts from wood, stone or silk,” he said. “And then the guests can purchase it.”