 In 2014–2015, Ai explored human rights and freedom of expression through an exhibition of his art exclusively created for Alcatraz, a notorious federal penitentiary in San Francisco Bay.Ai's @Large exhibit raised questions and contradictions about human rights and the freedom of expression through his artwork at the island's layered legacy as a 19th-century military fortress.Chinese artist and activist Ai Weiwei has used thousands of life jackets in two different installation to draw attention to refugees who have drowned while trying to reach Europe.