One of China's most famous dissidents has appropriated the United States' most famous former prison as a way to highlight the plight of activists held in detention.

Starting Sept. 27, the former island penitentiary turned U.S. national park in San Francisco Bay will offer visitors the opportunity to view seven installations custom-designed by the artist and activist Ai Weiwei.

Ai, for decades a critic of the Chinese government's record on free speech and human rights, created the pieces without ever having visited Alcatraz. He has been banned from leaving Chinasince his 81-day detention there in 2011.

The exhibit, called @Large, reflects the sting and isolation of detention with works like the massive "Trace," featuring portraits of 176 activists and political prisoners built entirely from 1.2 million Lego bricks.

"When people are detained for their beliefs, you get a sense of isolation, that you're being forgotten by the world," said Cheryl Haines, founding executive director of the FOR-SITE Foundation, organizer of the exhibit.

"It's his eloquent way of saying 'We have not forgotten about you,'" Haines said of Ai's "Trace."

Another work, "Stay Tuned," spans 12 single-block cells, each outfitted with a stool and speakers that play a different recording from artists who have been detained, including the Russian feminist punk band Pussy Riot.

After Haines approached Ai about creating an exhibit at Alcatraz, the entire project came together in about 9 months, much faster than the typical two- to three-year time frame.

The artist is subject to travel restrictions and it is unclear when they will be lifted. When asked why Ai was not allowed to attend the event in San Francisco, China's Foreign Ministry spokeswoman Hua Chunying said she does not understand "the relevant situation."

"China is a country ruled by law," Hua said. "The relevant departments, in accordance with Chinese laws and regulations on entering and exiting the country, deal with the entry and exit of Chinese citizens."

The Alcatraz exhibit expands on themes Ai, 57, had explored throughout his career as well as in an exhibit earlier this year in Berlin, which featured a reproduction of the white cell where he was held by Chinese authorities. In the latest work, the focus remains more on the experiences of other detainees.

The installations cover four areas in Alcatraz, including three that are typically blocked from the public.

The infamous former prison, with thousands of visitors a day, also hosts a bird sanctuary, making it necessary for organizers to assemble the works without the machinery they might have otherwise used.

"Refraction," a five-ton sculpture that incorporates teapots and reflective panels from solar cookers in Tibet, required painstaking manual labor to install. The sculpture also stands behind Plexiglas, partly to avoid disturbing the Brandt's Cormorant birds nesting nearby.

Ai is best-known for his part in designing the Bird's Nest stadium for the 2008 Beijing Olympics.