That issue looms large as migrant workers are exposed to, and overwhelmed by, inequality - it is a time bomb that has its roots in Shenzhen's meteoric rise, he said.

About 35 years ago, Shenzhen was a sleepy fishing village. However, since 1979, when it was designated as the country's first special economic zone, the city has become the showpiece of the fastest urbanization in history.

"Though 'Let some people get rich first' was the famous instruction for China's market reforms, it's hard to deny that our society is becoming worryingly unequal. One of the most extreme and often overlooked side effects has been Sanhe," Chen said.

In Longhua, it's almost impossible to find a new housing development with apartments that cost less than 60,000 yuan per square meter. "That figure may sound unimaginable and meaningless to low-paid migrant workers.

"It has become increasingly difficult for second-and third-generation unskilled, low-tech immigrants to find a place in Shenzhen, as the city no longer makes its fortune by churning out cheap, labor-intensive clothes, electronics and toys for foreign brands," Fang said.

"Those deemed good-for-nothing and incapable of creating value and making a contribution may end up being abandoned to their fate. That includes people at Sanhe, who are being discarded and forgotten."

News of Sanhe's sagging fortunes has trickled in almost every other month this year.

"I've heard the labor marketplace is now on the wane, and the urban villages in the central district of Shenzhen are disappearing to make way for lucrative commercial and residential projects," Xu said. "I've also heard that the days are numbered for so-called low-end immigrants like me in some cities."

But Shenzhen should be different, he said.

Fang hopes that Shenzhen's craze for skyscrapers will never come at the price of excluding migrant workers.

"A combination of urban villages, the labor marketplace and Sanhe dashen reflects the other half of the world in Shenzhen. We should never lose our awe and understanding of the city's dizzying economic growth."

Contact the writer at sophia@chinadailyhk.com