The ancient city of Dresden, a delicate baroque confection lovingly reconstructed after the Second World War, has thrilled visitors with its skyline, best viewed from the banks of the River Elbe. Not for much longer. To the outrage of conservationists, work is underway on a new bridge to carry a four-lane highway across the valley, marring the vista forever. In a potent gesture of protest, UNESCO recently stripped the city of its status as a World Heritage site.

Some might consider that a harsh penalty. After all, the World Heritage ranking placed Dresden alongside the Great Wall of China and the Taj Mahal as a monument of "outstanding universal value." But to the locals, ridding the city of choking traffic was more important than any accolade. In two referendums, they supported the bridge plan. As city councilor Jan Mücke said, "In a democracy, we cannot have a dictatorship of a minority that, acting out of esthetic grounds, thinks they know more than the overwhelming majority of citizens."

World Heritage status sure isn't what it used to be. Plenty of countries still strive to earn a place on UNESCO's list and reap the benefits of the tourism boom that normally follows, but some are beginning to question the honor's long-term value. In the developed world, there's sometimes resentment at outside interference; elsewhere there's deepening concern that the scheme, intended to preserve the world's greatest treasures, may actually be contributing to their demise. Underfunded and armed with little more than moral authority, UNESCO can't do much to help the swelling number of sites—the tally now approaches 900—it singles out for distinction. "Among conservationists there is sometimes a feeling that if conservation is the goal, then we should leave these places alone," says Peter Fowler, a British archeologist who has worked with UNESCO.

Trouble is, conservation is not always the goal. For national governments and local traders, a World Heritage listing represents a marketing tool that can turn obscure sites into must-see destinations. The repercussions are hard to prevent. In the ancient western Chinese city of Lijiang, the number of annual visitors climbed from 1.7 million to 4.6 million in the 10 years since it was listed in 1997. In the words of a UNESCO mission last year, "Commercial interests have driven measures to facilitate large numbers of tourists, compromising the authentic heritage values which attracted visitors to the property in the first place.''

The same is true of Angkor Wat, the vast temple complex that is now Cambodia's leading tourist draw. Since the site gained World Heritage status in 1992, the number of visitors has leapt from fewer than 10,000 to more than 1 million a year. Now a sprawling town has grown up to serve the hordes of tourists that arrive daily. Worse, local hotels have been extracting water from underground reserves, threatening to undermine the temples themselves. "Being a World Heritage site can contribute [to visitor numbers] between 10 times and 500 times over five years," says Jeff Morgan of the Global Heritage Fund. "Instead of a small paragraph in Frommer's, it suddenly gets three pages. And if a site is not ready, you can get thousands of people crawling over it."

There is no question that UNESCO can exert a positive influence. The organization can be "discreetly effective" in preventing the worst depredations, says Francesco Bandarin, director of the Paris-based World Heritage Center, which runs the list. If the Great Pyramids of Giza can be seen against the sunset without a highway marring the view, tourists can thank pressure from UNESCO. Still, Bandarin concedes, "We can provide one more layer of protection, but it's far from perfect."

Resources are severely stretched. The World Heritage Center employs fewer than 100 people, and its annual revenue of some $20 million, including donations, leave nothing to help poor countries struggling to save sites. "It needs 10 times as much money," says Morgan.

Some national authorities resent UNESCO's meddling. UNESCO can place listed sites that it believes are being compromised on an endangered list and, in extreme cases, scratch them altogether—a punishment applied only twice in the program's 37-year history. In addition to Dresden, an oryx sanctuary in Oman was struck off in 2007 after the government reduced the park's size by 90 percent to allow for oil drilling. UNESCO's decision to place Yellowstone National Park on its endangered list in 1995 after a private company proposed mining for gold nearby fortified American mistrust of U.N. interference—and helps explain why the U.S. has since failed to propose any new sites.

One option might be to restrict the list and focus resources on those most in need. In the past five years UNESCO has added more than 100 sites—including 13 this year alone—which only undermines the concept, say critics. "The longer [the list] becomes, the more it dilutes the brand," says Jonathan Foyle of the World Monuments Fund. Already it's hard to see what unites, say, a volcanic island off Iceland, Namibian rock paintings, and the Sydney Opera House.

Competition between countries—Italy and Spain have long vied for the largest number of sites—has already forced UNESCO to limit the number of new nominations per country to just two a year. Yet the organization is keen to encourage more applications from outside Europe and North America—home to more than half the sites—to correct what's been seen as a Western bias. At fault may be the very idea of highlighting a site's particular merits. In the end, the best hope for saving the legacy of the past may be a future of obscurity.