Beijing has announced plans to rebuild some of the gates in its long-lost imperial city wall: such is the way of heritage in China, where conservation often means demolition and putting up a replica.

The authorities are promising to restore the original appearance of the monumental Ming and Qing dynasty arches in the wall, which was demolished in the 1950s and stood where a ring road and metro line now run.

It is a hollow pledge. The landscape is so changed that even though China has excelled at copying for centuries, Beijingers have lined up to rail against the "fake antiquities" project.

A prime example is the Qianmen district, south of the Forbidden City. It was demolished during the giant renovation of the capital before the 2008 Olympics, then rebuilt as a historical theme park, complete with neon adverts for major international brands.

Since then, the practice of making a clean sweep of the past and rebuilding an inauthentic version, for instance with fake glazed roof tiles and kitsch hanging lanterns, has been dubbed "qianmenisation".

"It is an ignorant, stupid and greedy practice" said He Shuzhong, founder of Beijing's Centre for the Protection of Cultural Heritage.

"Ignorant because they do not know the meaning of cultural heritage; stupid, because they do not understand the old city's crucial role for society, and greedy because corruption permeates every step of the reconstruction."

Now Beijing's ancient Drum Tower and Nanluoguxiang areas have fallen victim to the bulldozers and are in the throes of "qianmenisation".

Others have already been transformed into "movie sets", as Hua Xinmin, activist and author of the book "I refuse to see my homeland disappear", puts it.

She is fighting an unequal battle against developers and local Communist officials who enrich themselves by destroying old neighbourhoods: they openly flout the law and forcibly evict residents, who often receive little in the way of compensation.

"It would be better to spend the money to preserve what is left instead of trying to remake what doesn't exist any more," she said, pointing out that two-thirds of Beijing's 3,000 old "hutongs", or alleys, have already vanished.

She is furious that the US weekly Time included Chen Lihua, a property magnate who destroyed her old Beijing neighbourhood, on its list of 2012's most influential people in the world.

The cycle of evictions followed by demolitions happens in every city in China.

In the the far west of the country, the Silk Road city of Kashgar is having its historic centre gutted and its traditional brick and mud houses replaced by new-builds, despite cries of alarm abroad.

But online social networks are now enabling better organised resistance -- Hua's microblogging feed has almost 15,000 followers.

During the Chinese New Year holidays the former Beijing home of renowned architect couple Liang Sicheng (1901-1972) and Lin Huiyin (1904-1955) -- ironically pioneers of saving Chinese cultural heritage -- was demolished, provoking outrage online.

It is now impossible to approach the site where the residence, which was in theory a protected listed building, stood. The area is controlled by developers, an AFP reporter saw, with security guards preventing access and a fence blocking the view.

"There is nowhere for future generations to remember their work," lamented Yu Wei, a passer-by.

In the city of Chongqing, the former residence of Nationalist China leader Chiang Kai-shek recently fell victim to an official "preventive demolition".

The move triggered widespread criticism -- and the authorities have meekly promised to rebuild it.