Sol LeWitt, Wall Drawing #1136, 2004

Sol LeWitt's Wall Drawing #1136, 2004 has been executed by members of the gallery team according to the late artist's instructions; it's a huge, vibrant and colourful abstract painting which is painted directly onto the gallery wall and therefore only exists for the duration of its exhibition. When the exhibition is over, the painting will be painted over again (until it's painted in some other gallery some other time.)