Swiss architect Peter Zumthor has won his profession's top honour, the Pritzker Architecture Prize.
Zumthor, 65, is best-known for the Therme Vals project, a luxury spa that opened in 1996 after a decade of work. It consists of 60,000 precision-cut quartzite stone slabs built into a hillside surrounded by alpine peaks.
He also designed the Kolumba art museum in Cologne and a chapel on a nearby farm. In Austria, he designed the Kunsthaus Bregenz museum.
The Brother Klaus Field Chapel consists of a concrete shell layered over a conical tent of 112 tree trunks that were later dried out and removed, leaving a blackened interior.
Zumthor is based in the village of Haldenstein, in the canton of Graubuenden. He is the third Swiss to receive the prize.
The Pritzker Prize was established in 1979 by the Pritzker family, of Chicago, which owns the Hyatt hotel chain.
The prize - a bronze medallion and $US100,000 - is presented at a different location each year. This year's ceremony will take place in Argentina on 29 May, at the legislative palace of the Buenos Aires City Council.