It’s rather appropriate that Ai Weiwei’s newest exhibition, "@Large," opening Sept. 27, is being mounted at Alcatraz. For the show, the first art exhibition on the San Francisco island, Ai will install his creations behind the bars of the former prison. If there’s one thing the artist is known for other than his large-scale creative visions (he collaborated with noted architects Herzog & de Meuron on Beijing National Stadium), it’s his outspokenness on political matters, a habit that landed the artist in solitary confinement for 81 days. While “creative freedom” isn’t the first concept that comes to mind when one thinks of a prison, Ai is just the latest in a long line of artists who have played on the concept of incarceration as a creative device. Whether they’re creating art from behind bars or on the outside looking in, here are 15 Prison Art Projects.