No one knows why some ancient civilizations 2000 years ago etched the elaborate shapes of a 50-meter-long spider and 100-meter-long monkey in the desert to the south of Lima.

The maze of mysterious lines and figures which can only be seen by air attracts numerous tourists worldwide to the Nazca lines, one of Peru's World Heritage sites. However, they are only allowed to see it from helicopter. Approaching the Nazca lines by walking and driving is forbidden to avoid possible damages.

The ongoing 28th session of World Heritage Committee here urges the world to find balance between tourism and preservation of heritage sites such as the Nazca lines did.

"World Heritage sites should be open to people, because, first, we have both the right and the obligation to learn from our ancestors, and second, tourism income can fund heritage preservation," said Du Yue, deputy Secretary-General of Chinese National Committee for the United Nations Educational, Scientific and Cultural Organization (UNESCO).

However, Mechtild Rossler, chief of cultural landscapes for the UNESCO World Heritage Center, believes that over-exploitation for tourism may damage the unique inheritance of the sites and threaten local cultures.

According to a book published by the World Conservation Union, tourism's adverse impacts include ecological damages caused by construction, tourists and vehicles, water pollution, robbery and damages of cultural relics.

"Excessive tourism will bring disaster to heritage sites. It's crucial to establish balance between tourism and preservation," said UNESCO Director-General Koichiro Matsuura.

Lu Zhou, an architecture professor of Qinghua University, believes the priority is to limit the number and behaviors of tourists.

Yellowstone Park in the United States was put on the endangered heritage list in 1995, because heavy visits had severely disturbed wild animals. Nowadays, tourists have to draw lots to decide who can go into the park.

Receiving 700 million tourists every year, China began to learn from foreign experience to protect its pressured sites. In the Dunhuang Grottoes of northwest China's Gansu Province, tourists have to make a reservation to see the endangered frescos.
 
(Xinhua News Agency July 1, 2004)