Since the end of the 20th century, an unprecedented number of remarkable museums have been built. None have had bigger worldwide implications than Frank Gehry's Guggenheim Museum in Bilbao (199197). Until, that is, the new Musee des Confluences in Lyon was opened to the public, in late 2014. It was created by Wolf D. Prix of the Coop Himmelb(l)au team, which was founded in the 1970s. Many avant-garde groups from those wild years such as Archigram, Superstudio, Archizoom, Haus-Rucker-Co, and the Japanese Metabolists are now consigned to the past, but the Coop Himmelb(l)au architecture firm, whose special aspiration was always to bring into the world buildings that overcome the pull of the earth buildings 'to float on the horizon like clouds' is more in demand than ever. The finest demonstration of this endeavour to date can now be admired in Lyon. Functioning as a museum of human history, this impressive concrete, metal and glass colossus truly does appear to float above the peninsula at the confluence of the Rhone and the Saone. Like the Guggenheim Museum in Bilbao, this new building, so impossible to overlook, is an inspiration for the revita-lisation of disrupted urban areas and the valorisation of derelict industrial areas within the city precincts, but also far beyond Lyon. This Opus volume deals with the origins, construction, function and formal appearance of the Musee des Confluences, and also offers a preliminary theoretically based evaluation of the architecture of the building. Frank R. Werner was professor of history and architecture theory at the Staatliche Akademie der Bildenden Kunste Stuttgart from 1990 until 1994 and director of the Institut fur Architekturgeschichte und Architekturtheorie at the Bergische Universitat in Wuppertal from 1993 until his retirement in 2012. He studied painting, architecture and history of architecture in Mainz, Hanover and Stuttgart. Christian Richters studied communication design at the Folkwang-schule in Essen. He is one of the most sought-after architecture photographers in Europe. To date he has been represented in the Opus series by 14 volumes, including ones about the embassies of the Nordic countries and the Bode Museum in Berlin, the Nieuwe Luxor Theater in Rotterdam and the BMW Welt in Munich. See also: Opus 66. Coop Himmelb(l)au, BMW Welt, Munchen, Edition Axel Menges 2009.