The Hadian detention centre northeast of Beijing is a vast industrial-like complex.
It has some 4,000 inmates including three women whose names and faces are making headline news around the World.
Wei Ting Ting, Li Ting Ting (no relation) and Zheng Churan were arrested on March 6, along with two activists who are now being treated in a police hospital.
Wu Rongrong has hepatitis B; Wang Man a heart condition, allegedly brought on by her interrogation. The group were detained ahead of a protest they were planning to hold two days later to coincide with International Women’s Day.
They had sought to hand out leaflets to highlight a campaign against sexual harassment on public transportation.
That may not sound particularly radical, but in today’s China that kind of thing can get you into a lot of trouble.
The women knew they were on the authorities radar, but it is probably fair to assume they didn't expect it would lead to weeks of incarceration in a grim detention centre - especially since China’s government recognises Women’s Day.
After all, it was no lesser authority than Chairman Mao, China's communist leader, who once declared that "women hold up half of the sky".
Wei Ting Ting is a high profile advocate of gay and women’s rights as well as openly bisexual.
In recent weeks the 26-year-old has taken part in cheeky stunts that have helped to raise awareness on issues ranging from domestic violence to more public toilets for women.
But her lawyer, Wang Qiushi, who looks even younger, is astonished by the outcome this time.
"I was shocked," he said. "Such a gentle way to express themselves, can be cracked down like this, can trigger so much response from the authorities. I’m puzzled. This sends us a message."
That message is: dissent of any kind will not be tolerated.
I met Wang as he was heading to the Hadian detention centre for what would be only his third meeting with his client.
"Wei Tingting is in a not bad shape. Her interrogation, her health, are ok. The intensity of her interrogation is considered tough I guess, in general. When I saw her last week she said she was often interrogated until midnight. She’s short-sighted but is not allowed to wear her glasses. This causes great inconvenience because she can’t see the written record of her interrogation."
Source: Al Jazeera