When 63-year-old Li Jinchen went to West Chang'an Avenue on a recent Saturday, he found a bulldozer hard at work on the 102-year-old post office located there. "It was this post office that delivered letters and newspapers to my home, and I used to buy a lot of stamps here for my collection," says Li, who lived near the post office for 50 years before his courtyard house was demolished in 1999.

Running east to west through Beijing and passing in front of Tian'anmen Square, Chang'an Avenue, or the Avenue of Eternal Peace, is one of the most important roads in China. It was built between 1406 and 1420 as part of the Ming Dynasty (1368-1644) layout for Beijing's Imperial City.

In Li's childhood, Chang'an Avenue was soaked in the atmosphere of old Beijing. Along it lay mostly low-roofed houses, except for the two towers of the 700-year-old Qingshou Temple where today's Beijing Book Building stands. Two pailou (traditional wooden archways) decorated the east and west sections of the street. Li recalls Xidan as a lively night market of food stands.

The towers and gateways have long vanished and the steet is now lined with huge, modern buildings. The section to the south of Xinhuamen used to be the widest part of the old Chang'an Avenue, but is now the narrowest, following the repeated widening of the other sections. The government has announced that after the new widening project, the number of lanes in this section too will be increased from eight to 10, as in other sections of the avenue.

"I understand that Beijing has to modernize, but I hope the government will make proper arrangements for the protection of cultural relics," says Li. "Though the buildings of this area do not come under national or municipal-level protection, some are still of important historical value."

Li has taken hundreds of photos of this area - of the marble arch of the defunct mosque, of a gray brick wall with carved patterns built in the 1910s, and of the stone posts in Dongshuan Hutong where Qing Dynasty ministers tied their horses before entering the Forbidden City.

A part of West Chang'an Avenue in Xidan being widened.

Li has been training his lens on Beijing's changes for more than 30 years, but for the last three years, besides keeping a personal record, he has also been contributing to the protection of China's cultural heritage.

Li joined the website www.memoryofchina.org in 2006 and is now moderator of its Beijing sub-forum. After photographing West Chang'an Avenue, he posted his photos on the forum. They triggered a hot discussion among members of the forum, most of whom expressed concern and regret at the loss of a historical site.