So, in late 2011, when Ai’s friend and colleague Cheryl Haines, director of the For-Site Foundation—a San Francisco nonprofit dedicated to contemporary, place-based art—casually offered him “a prison to work with,” he accepted the challenge of generating site-specific art for a place he couldn’t visit. This would not, however, be the first time Ai would create installations for spaces where he’d never set foot: For the 2013 Venice Biennale, he re-enacted scenes from his own incarceration in large, iron-clad dioramas inside a Venetian church; and, earlier this year, his solo show in Berlin transformed 18 rooms and a sunken courtyard at the Martin-Gropius-Bau. His capacity to visualize such projects from thousands of miles away, says Haines, attests to “Weiwei’s extraordinary understanding of space and the built environment.” (Though not formally trained as an architect, he collaborated with Herzog & de Meuron on the Birds’ Nest stadium for the 2008 Olympics in Beijing and also designed and built live-work compounds for artists on the city’s outskirts.)

But offering a prison is one thing, and delivering it quite another. Haines’s first hurdle was to obtain permission from the National Parks Service (NPS) and Golden Gate National Parks Conservancy (GGNPC), the agencies that oversee the former penitentiary (decommissioned in 1963)—and regularly turn down proposals for artistic interventions there. While NPS superintendent Frank Dean and GGNPC president Greg Moore instantly gravitated to the idea of an Ai Weiwei installation at Alcatraz, Dean prudently sought State Department approval. “We didn’t want an international incident to emerge from what we thought was a good idea,” he explains. (Though the exhibition’s specific content was yet undetermined, Washington issued its go-ahead within days.)

Then came the daunting task of familiarizing Ai with a penitentiary 6,000 miles from his studio in Beijing. That process involved walk-through videos, Skype conferences, detailed 3-D drawings, vintage photos, in-depth research, and multiple trips to Beijing by Haines (who stuffed her suitcases with everything from Hollywood movies about Alcatraz to a facsimile prison key). She also raised $3.5 million, mostly from private sources, to cover the show’s costs.

One of the real achievements of @Large, a seven-part installation in various parts of the historic buildings, is how it alters and heightens our perception of an already powerful venue. And the title @Large, coined by the artist, does not merely nod to essential role of the Internet in his (and much of today’s) political activism, but also ironically borrows a phrase that can mean “at liberty” or, conversely, “escaped and not yet captured.” At Alcatraz, the artist was permitted to engage spaces usually off limits to visitors (partly for the practical reason of keeping his installation from interfering with the regular, ongoing penitentiary tour). Among those newly opened venues are the prison hospital; New Industries Building; and A-Block Cells, the only unaltered, early 19th-century cell block from Alcatraz’s days as a military prison, prior to its conversion, in 1934, to a federal penitentiary. Holders of ferry tickets to the island are permitted to enter all permanent and temporary exhibitions there, free of additional charge.

The New Industries structure—once bustling with guarded convicts laundering barge-loads of military uniforms, on an island with no water source of its own—houses three of Ai’s most ambitious installations: With Wind, Trace, and Refraction. Illumination and Blossom are sited in the prison hospital, Stay Tuned in the A-Block cells, and Yours Truly in the penitentiary dining hall.

For Trace, he paved a large, raw industrial space with 176 blown-up portraits of political exiles and prisoners constructed from 1.2 million Legos. As the title suggests, many of these people have vanished with barely a trace, other than a grainy photo. Here, the mix of images—snapped together, according to the artist’s blueprints, by a legion of local volunteers—includes such celebrated historic figures as Nelson Mandela and Martin Luther King, Jr., along with current, little-known prisoners of conscience across Asia, Africa, Latin America, and the Mideast, as well as such controversial Americans as Edward Snowden and Chelsea Manning. This grouping—audaciously presented on United States federal property—spares no distinction between our government and the world’s most brutal regimes.

Trace is a display as bluntly unvarnished as a mug shot, yet at the same time, like the paper dragon in the next room, it enlists pleasurable children’s toys to expose turbulent themes. In an interview conducted by Haines, available on line, Ai describes some of his intentions: “To carry the essential ideas about freedom, to let everybody, even children, appreciate it, we have to make it beautiful, we have to make it fly.”

But in the bowels of the New Industries Building, the bird of freedom is not merely tethered like a kite, but virtually leaden. Here, Refraction presents an abstract bird wing, weighing more than five tons, cobbled together from cheap Tibetan cookware and solar cooking panels, all trapped in this nearly sunless space. We are never actually permitted to enter that room, but view it only through broken glass and grates from a surveillance gallery once manned by armed guards. Generating an uneasy tension, this vantage point casts the viewer in the controlling role of authority, while simultaneously confining us, like prisoners, within this narrowly claustrophobic passageway.

Risk-taking and streaked with irreverence, the exhibition sometimes verges tacitly on moralizing. But at its best, this work focuses our attention, almost viscerally, on little-known political prisoners and what Ai has described as the great irony “that people fighting for freedom are being incarcerated.” And here, as Moore points out, “we have an historical place that was considered inescapable, hosting an artist currently under house arrest—whose work has traveled the world.”