This autumn, guests can not only view the art, but they can play with it too. Martin Creed’s No.200: Half the Air in a Given Space, to be offered in Sotheby’s Contemporary Art Day Auction on 18 November, features white balloons occupying half the volume of the space containing them. Come to Sotheby’s before the pre-sale exhibition closes on 17 November to step inside and experience this buoyant installation for yourself.