The sudden death of world treasures sometimes arises from natural causes or old age, but more often it is the result of what we humans are doing, or failing to do. And what we do, we can undo—or do better. In other words, their fate is in our hands.

There are certain places (like Beirut and Bali) that seem permanently on the brink of extinction but which have shown a great capacity for surviving anything, even their own obituaries. There are other wonders (like the Buddhas that once graced Afghanistan's Bamiyan Valley) that are unquestionably gone forever. If you believe, as I do, that the medieval palaces of Baku, the languid beauty of the Everglades, the desert tombs of Luxor, and the turquoise seas of Indonesia's Coral Triangle belong to us all, then it only follows that the loss of any of these will be a tragedy for us all. If we do not act now, our memories could too soon turn into real elegies.

Bagan, Myanmar
Brand-new temples modeled (loosely) on the originals threaten to ruin one of Asia's most spectacular sites

When the sun begins to dip in Bagan, a vast complex of ancient ruins dotting Myanmar's sun-scorched central plain, visitors rush to climb Shwesandaw Paya, a pyramid-shaped temple covered in chipped white plaster and crowned in gold leaf. Often called the Sunset Pagoda, Shwesandaw has five terraces, each affording panoramic views of the plains, the Irrawaddy River, and the Archaeological Zone's more than 3,000 monuments. The vast majority date back at least 800 years, but hundreds of others have been hastily constructed in the last 15.

Once considered among the most precious collections of relics in Southeast Asia, second only to Cambodia's Angkor Wat, Bagan (formerly Pagan) is in danger of becoming an unmitigated disaster, say archaeologists. An eleventh-century king is credited with building many of the original shrines, ornamenting what was then Myanmar's royal capital with symbols of his religious fervor. After a 1975 earthquake damaged several of the most important temples, government officials invited a team of UNESCO archaeologists to help restore and reinforce the monuments, and Bagan seemed well on its way to becoming a World Heritage Site.

But by the early 1990s, Myanmar's notoriously ruthless military regime was no longer interested in adhering to the exacting UNESCO standards for historic preservation, choosing instead to fast-track the restorations and erect replicas of monasteries, stupas, and temples—many from scratch and with inferior materials—in an effort to lure more visitors to the country's most popular tourist attraction.

"The real crime is that the temples are being rebuilt without attention to their original appearance," says art historian Donald Stadtner, author of Ancient Pagan: Buddhist Plan of Merit. Unskilled workers are paid a dollar a day to build generic-looking shrines, often atop the unexcavated medieval ruins. The original stupas took months or years to construct, but the modern facsimiles are now completed in two weeks. Most of the original Buddha statues have been replaced with period reproductions—although the "periods" are typically off by several hundred years. One of the worst blunders is in Bagan's only surviving Hindu temple, Nat Hlaung Kyaung, where three exquisite sculptures of Vishnu, accidentally destroyed in the 1990s, were replaced with inelegant cement replicas, one of which has six arms instead of four.