Ai Weiwei, China’s best-known dissident artist, has a new exhibit, ‘@Large: Ai Weiwei,’ at the former island prison of Alcatraz that pays tribute to dozens of political prisoners and political exiles around the world. The Alcatraz exhibition features portraits in toy Lego bricks of 176 political prisoners and exiles. Crews in China and in San Francisco assembled the portraits on Alcatraz under Ai’s direction using 1.2 million Legos. Alcatraz was closed as a federal penitentiary in 1963 and is now overseen by the National Park Service, which helped arrange and host the exhibition. The exhibit runs through April.