WHILE most Beijing residents rush through the capital's golden and crimson archways, Zhang Zhenhua steps into their broad shadows and into times gone by.For eight years the factory worker has trudged down Beijing's hundreds of gray-stone alleys, chronicling details of old neighborhoods and pailou or decorated arches. Most importantly, Zhang has preserved the folk ideas and values behind Beijing's worn walls by recording the homilies that Chinese carved or scrawled on their gateposts before the communist revolution. Notebook and camera in hand, Mr. Zhang devotes all his spare time to his self-appointed mission. He manages to stay one step ahead of the wrecking ball. Beijing in the past decade has smashed to rubble many pailou and small neighborhoods that had stood for centuries. In their place, the city has thrown up concrete apartment blocks resembling cardboard shoe boxes upended against the skyline. Zhang admits his notebooks cannot stop the bulldozers. But they can ensure that the capital's historic neighborhoods do not crumble into complete oblivion, he says. "There are so many old, magnificent, and priceless buildings and neighborhoods in Beijing," according to Zhang, a founder of the Society of Beijing History, Geography, and Folk Customs. "Being members of the younger generation, we should learn more about our cultural heritage," says Zhang, a worker at a factory that makes machines for the textile industry. This is not the first time Zhang has preserved part of old Beijing from the communist leadership's obsessive campaigns for "progress." In the mid-1960s, Zhang heeded the call of Mao Zedong and joined millions of youths across the country in the Cultural Revolution (1966 to 1976), an ultra-radical firestorm aimed at destroying all vestiges of traditional China. Like other Red Guards, Zhang quit high school and took to the streets in massive, militant demonstrations. But as he watched fanatics melt down ancient bronze Buddhas and destroy other cultural relics, he began to have misgivings. Rather than challenge the young iconoclasts, Zhang volunteered to work at a paper factory that was assigned the politically glorious task of turning stacks of old, "reactionary" books into pulp. "The destruction of so many fine books was unbearable to watch," he says. Over the course of several months he slipped out of the factory with dozens of yellowed books on history, art, and other taboo subjects. At home, living among the rescued books, Zhang began to read and gradually acquired a harlequin version of the education that had been so severely disrupted. After a tour in the Army, Zhang returned to his hometown and began cataloging Beijing's huddled alleyways or hutongs, the long and narrow neighborhoods that fleck the sprawling city. Zhang discovered some 3,000 of the lanes, 1,000 more than on official maps, and wrote down their names and any local lore. "The names of the hutongs tell us everything about Beijing; they are a small-size encyclopedia of politics, economics, culture, plants, animals, and geology," Zhang says. For instance, the name of the Liyu hutong honors the young, rural scholars who during dynastic China journeyed to Beijing from villages across the country to take the imperial exams. If the peasants passed the rigorous exam, they were said to be like fish or yu, who had jumped over the "dragon's gate" or risen from a low class to a high one through their own exertions. Each of Beijing's pailou also tells a story and they are a tribute to the elaborate grandeur of China's architecture, Zhang says. The structures evolved from simple gates in ancient times, to gates with roofs, to intricately ornamented arches of ceramic or carved wood with several stories and portals. Before the Communist Party came to power, Beijing had more than 300 pailou; now there are about 110 of the archways. "I am afraid Beijing will lose its extraordinary character because of modernization and construction," Zhang says. Still, Beijing has more pailou than any other city, he adds. While trying to preserve the architectural body of Beijing, Zhang has also sought to sustain its traditional spirit. In his rambles down city alleyways, he has recorded 587 menlian or couplets carved or painted on the gateposts of the former homes of well-to-do families. The fading menlian are a digest of the traditional values that have been eroded by communist orthodoxy. They generally tend to celebrate the family, wealth, or harmony between man and nature, according to Zhang. "To keep a family together takes honesty, to leave an everlasting legacy takes books," says Zhang, quoting one of his favorite couplets. He plans to follow the maxim and publish a book on the findings of his peregrinations in Beijing. The menlian that have survived four decades of tumultuous communist rule offer a rough profile of city residents before the revolution, according to Zhang. In parts of east Beijing, where wealthy merchants and businessmen lived, the couplets extol riches. In west Beijing, where educated and culturally minded residents made their homes, the menlian glorify themes like respect for elders, Zhang says. Zhang fears that the steady razing of gateposts with couplets is just one of the more vivid signs of how Chinese are eradicating traditional values in their hearts. "The disappearance of the menlian could mean that less people will follow the advise of the couplets," according to Zhang. "But the menlian are part of China's precious cultural heritage; they should be preserved."