Preservation: Sure, It's a Good Thing, but..

The phrase Unesco World Heritage site has been crossing from the lips of travel agents and popping up more and more on travel Web sites. That's no coincidence: the list has grown steadily from the first 12 in 1978 to 812 today, and includes everything from the Statue of Liberty, the Taj Mahal and Angkor Wat to the Wooden Churches of Southern Little Poland and the Orkhon Valley Cultural Landscape in Mongolia.

But as the list expands each year, many, including Unesco staff members, are left wondering: is this rapid growth watering down the list's meaning? And by drawing both tourism and development that's often left unchecked, can the honor do as much harm as good to those places so anointed?

Although Mexico devotes more resources to the World Heritage efforts than many countries, the Yucatán provides lessons in what can happen after a site makes the list. Mexico's most emblematic site is probably the ancient Maya city of Chichén Itzá, which by the time it was inscribed was already overrun with tourists on day trips from Cancún, three hours to the east. The numbers grew after nomination, with peak months bringing more than 5,000 visitors a day, according to Yucatán government statistics.

Standing before Chichén Itzá's iconic Kukulcan pyramid is still stunning, to be sure, but watching the line of tour buses spewing forth American tourists outside is just as remarkable. Visitors emerge with stickers on their shirts identifying their bus numbers. Cheery guides with set scripts shepherd them through the gate, where they are given official admission wristbands.

Beyond the gates, souvenir hawkers are well trained. One regular, Ermenegildo Kahum Kem, knows how to say, "Nothing for your mother-in-law?" in five languages.

Unesco's manifesto sounded simple enough: It set up a World Heritage Convention in 1972 to protect cultural and natural sites of "outstanding universal value." The convention established a World Heritage Committee, a rotating group of 15 (now 21) nations, and a World Heritage Fund to provide oversight, technical assistance and loans. The World Heritage Center in Paris oversees the program, and the committee annually decides on new designations.

It has become clear, though, that for many sites, getting on the list might be more an end goal than the beginning of conservation efforts. Once the four- to five-year nomination process is over, Unesco generally doesn't provide funds or technical assistance from its 35-person staff (plus consultants), nor regular monitoring to ensure that the ambitious plans come to fruition.