Zumthor founded his own firm in 1979. His practice grew quickly and he accepted more international projects.
Zumthor has taught at Southern California Institute of Architecture in Los Angeles (1988), the Technical University of Munich (1989), Tulane University (1992), and the Harvard Graduate School of Design (1999). Since 1996, he is professor at the Accademia di Architettura di Mendrisio
His best known projects are the Kunsthaus Bregenz (1997), a shimmering glass and concrete cube that overlooks Lake Constance (Bodensee) in Austria; the cave-like thermal baths in Vals, Switzerland (1999); the Swiss Pavilion for Expo 2000 in Hannover, an all-timber structure intended to be recycled after the event; the Kolumba Diocesan Museum (2007), in Cologne; and the Bruder Klaus Field Chapel, on a farm near Wachendorf.
In 1993 Zumthor won the competition for a museum and documentation center on the horrors of Nazism to be built on the site of Gestapo headquarters in Berlin. Mr. Zumthor’s submission called for an extended three-story building with a framework consisting of concrete rods. The project, called the Topography of Terror, was partly built and then abandoned when the government decided not to go ahead for financial reasons. The unfinished building was demolished in 2004. In 1999, Zumthor was selected as the only foreign architect to participate in Norway’s National Tourist Routes Project, with two projects, the Memorial in Memory of the Victims of the Witch Trials in Varanger, a collaboration with Louise Bourgeois (completed in 2010), and a rest area/museum on the site of an abandoned zinc mine.
For the Dia Art Foundation in Beacon, New York, Zumthor designed a gallery that was to house the “360° I Ching” sculpture by Walter de Maria; though the project was never completed. Zumthor is the only foreign architect to participate, with two projects, the Memorial in Memory of the Victims of the Witch Trials in Varanger, a collaboration with Louise Bourgeois (to be completed in June), and a rest area/museum on the site of an abandoned zinc mine (completion date 2011). In November 2009, it was revealed that Zumthor is working on a major redesign for the campus of the Los Angeles County Museum of Art. Recently, he turned down an opportunity to consider a new library for Magdalen College, Oxford. He was selected to design the Serpentine Gallery's annual summer pavilion with designer Piet Oudolf in 2011.
Currently, Zumthor works out of his small studio with around 30 employees, in Haldenstein, near the city of Chur, in Switzerland.