Watch HDToday. Broodthaers’s first film, Clef d’Horloge was made using a borrowed camera and some film stock that he had been given. It was shot at the Palais des Beaux-Arts, Brussels, in 1956, during an exhibition of works by Kurt Schwitters. The film is made in negative and positive and is based on several works that were on display. It premiered on 23 April 1958 at ‘Filmexprmntlfilm’, an experimental film convention in Brussels.