On display at the Lisson is a replica of these cameras, but carved out of a single block of white marble. The work, entitled "Surveillance Camera", is a commentary on the Big Brother state in which Ai lives. It is pointed out of the gallery's vast window, seemingly recording the Lisson's own CCTV camera outside, or perhaps the schoolchildren in the playground across the road. In the light of his detention, the sculpture acquires an added depth. Ai had complained about the ubiquitous police surveillance in China just two days before he vanished.