He was exposed to art from a young age through his father's extensive collection, assembled between the late 1940s and 1980s and featuring works by Pablo Picasso, Henri Matisse, Marc Chagall, Le Corbusier, Olle Bærtling, Sam Francis, Mark Tobey and Lucio Fontana.
[1] Key modernist works in the collection included the two versions of Matisse's Apollo (1953), Picasso's Nude in a rocking chair (1956) and Chagall's Les mariés sous le baldaquin (1949).
Ahrenberg's introduction to contemporary art came through the atelier at the family property at Chexbres, where artists including Christo, Tadeusz Kantor, Enrico Baj, Jean Tinguely, and Niki de Saint Phalle lived and worked between 1962 and 1977.
[5] On 18 October 2012 Ahrenberg relaunched Cahiers d’Art with the first issue of its eponymous revue since 1960, dedicated to the work of Ellsworth Kelly and co-edited with Hans Ulrich Obrist and Sam Keller.
His current collection contains works by Picasso, Matisse, Kandinsky, Le Corbusier, Richard Serra, Robert Longo, Wolfgang Tillmans, Cildo Meireles, Jenny Holzer, Martin Kippenberger and Adrián Villar Rojas, among many others.