It was announced Tuesday that German architect and engineer Frei Otto, who died on Monday, won the 2015 Pritzker Architecture Prize. His firm's most notable works included investigations into tensile structures and organic forms. Here is a look at some of these projects.

For more on each project, click the link in the project name to see it in ARCHITECT's Project Gallery.

1972 Munich Olympic Stadium, Munich

Roofing for main sports facilities in the Munich Olympic Park for the 1972 Summer Olympics, 1968–1972 Munich, Germany
© Atelier Frei Otto Warmbronn Roofing for main sports facilities in the Munich Olympic Park for the 1972 Summer Olympics, 1968–1972 Munich, Germany

Mannheim Multihalle, 1974, Mannheim, Germany

Roof for the Multihalle (multi-purpose hall) in Mannheim, 1970–1975, Mannheim, Germany
© Atelier Frei Otto Warmbronn Roof for the Multihalle (multi-purpose hall) in Mannheim, 1970–1975, Mannheim, Germany

International and Universal Exposition, 1967, Montreal

The 1967 International and Universal Exposition or Expo 67, 1967, Montreal, Canada
© Atelier Frei Otto Warmbronn The 1967 International and Universal Exposition or Expo 67, 1967, Montreal, Canada

Otto Diplomatic Club Heart Tent, Riyadh, Saudi Arabia

Diplomatic Club Heart Tent, 1980, Riyadh, Saudi Arabia
© Atelier Frei Otto Warmbronn Diplomatic Club Heart Tent, 1980, Riyadh, Saudi Arabia

Munich Zoo Aviary, 1980, Munich

Aviary in the Munich Zoo at Hellabrunn, 1979-1980, Munich (Hellabrunn), Germany
© Atelier Frei Otto Warmbronn Aviary in the Munich Zoo at Hellabrunn, 1979-1980, Munich (Hellabrunn), Germany

Arctic City, 1970, concept proposal

“City in the Arctic” model
© Atelier Frei Otto Warmbronn “City in the Arctic” model

Hall at the International Garden Exhibition, 1963, Munich

Hall at the International Garden Exhibition, 1963, Hamburg, Germany
© Atelier Frei Otto Warmbronn Hall at the International Garden Exhibition, 1963, Hamburg, Germany

Japan Pavilion, Hannover Expo, 2000, Hannover, Germany

Japan Pavilion at Expo 2000 in Hannover, Germany.
Hiroyuki Hirai Japan Pavilion at Expo 2000 in Hannover, Germany.

Institute for Lightweight Structures at the University of Stuttgart, Vaihingen, Germany

Institute for Lightweight Structures, interior, 1967, University of Stuttgart in Vaihingen
© Atelier Frei Otto Warmbronn Institute for Lightweight Structures, interior, 1967, University of Stuttgart in Vaihingen

Umbrellas for Pink Floyd's Concert Tour, various locations across the United States.

Umbrellas for Pink Floyd’s 1977 concert tour of the United States, 1977
© Atelier Frei Otto Warmbronn Umbrellas for Pink Floyd’s 1977 concert tour of the United States, 1977

For more on each project, click the link in the project name to see it in ARCHITECT's Project Gallery.