2015 Pritzker winner and a pioneer in innovative lightweight structures, Frei Otto has done 60 years of relevant and useful research in materials, membranes and tensile architecture. Born in Germany, Otto spent 2 years in a French camp as a prisoner of war, where he worked as a camp architect, building temporary camps, after which he pursued a career in architecture and structural engineering. His work is democratic, inclusive of nature, lightweight, cost-effective, and durable.
Here are 15 such innovative projects designed by Frei Otto:
1. The Tuwaiq Palace by Frei Otto
The Tuwaiq Palace is a response to the unique opportunities presented by the site, a design worthy of the majestic promontory site overlooking the sweeping Wadi Hanifah below.
The building’s design designed by Frei Otto features a curving, 800-meter-long “Living Wall” that wraps around a lush garden, with five projecting tensile (tent) structures providing shade along the wall.
At the heart of the concept is the need for physical protection from the environment in contrast to the desire to view the unique panorama available from the site. The concept became one of a series of contrasts: light and heavy, garden and desert, modern and traditional technology, openness and solidity.

2. The German Pavilion
The German Pavilion was part of the Expo’s late-modern demonstration of the potential of technology, pre-fabrication, and mass production to generate a new humanitarian direction for architecture. This remarkable collection at the Expo was both the zenith of modern meliorism and its tragic swan song; never since has the world seen such a singularly hopeful display of innovative architecture. Otto believed that his tensile canopies promised an architectural solution that was cheap, durable, and highly versatile.

3. Olympic Stadium, Munich
A structure that continuously flows along the site mimicking the draping and the rhythmic elevations of the Swiss Alps, a structure suspended like a cloud that seems to float over the place branching between the pools, gym and the main stadium, the roof of the Olympic Stadium in Munich, which covers and unifies the stadium, tracks, and pools, was developed by Frei Otto based on the use of computerized mathematical procedures in determining their form and behavior.

4. Multihalle, Mannheim
It comprises of a filigree lattice structure that spans various spaces: a self-contained function room (the actual hall), walkways, open spaces, and various operating facilities. This timber grid shell roof – still the largest of its kind in the world – contains no right angles and molds into the park landscape in a biomorphic way. The Multihalle consists of two shells that are connected via a canopied walkway. The entire structure measures 160 x 115 meters; the highest dome point is 20 m above the ground. Its widest span is 60 m, its longest is 85 m. The shell construction consists of two resp. four layers of interlaced slats of Canadian hemlock wood placed 50 cm apart. Each lattice slat is 5.5 cm wide.

5. Institute For Lightweight Structures
An experimental structure was erected on the university campus in Stuttgart-Vaihingen in 1966 by Frei Otto to test the construction and assembly of the Montreal pavilion. The net has a mesh width of 50 cm and had been prefabricated in four strips which were then fitted together to form two symmetrical sections on the site and suspended within the peripheral ropes. The tubular steel mast was raised by a crane and temporarily guyed with ropes. The ridge and eye edge cables were fastened to the masthead and the net was drawn evenly and slowly up the mast. After standing for two years the experimental building was dismantled, re-erected 2kms away and extended for use as the home of the Institute for Lightweight Structures.

6. The Japanese Pavilion
The Japanese Pavilion for Expo 2000, held in Hannover, Germany, designed by Frei Otto was a grid structure made of recyclable paper tubes resulting in a building with honeycomb. The protection of the “environment” was the theme of the exhibition in Hannover and the concept developed for the realization of the Japan Pavilion was the creation of a structure whose materials could be recycled when it was dismantled. Ban designed a curved tunnel paper, supported by a matrix of tubes of recycled paper, thereby making it less technological construction possible. The wavy shape consisted of cardboard tubes, 440 12cm in diameter, with a length of 40 m. The membrane structure has also covered the paper, although it was necessary to add a PVC membrane for fire safety issues, made in Japan and consists of five layers of fireproofing and waterproofing, allowing natural light to enter the room.
7. Aviary, Hellabrunn
A visionary building is the Aviary, build in 1981. It measures 18 meters in height and an area of 5.000 square meters that is covered by a fine mesh of stainless steel. Inside is an idyllic landscape with a small stream where the birds can fly around freely just like in the wild.
8. Diplomatic Club Heart Tent
The curved walls of the tent-like structures involved a highly concentrated and intricate building process because the kind of technology used to build these tents was very limited. The redesign of this area also became equally intricate because of this.
The Diplomatic Club Heart Tents are placed by Frei Otto within the interior gardens of the palace and used for receptions and banqueting. They are made of cable net construction, with insulation and tile cladding, and are meant to blend in with both the garden and the exterior of the surrounding palace. However, the tents also face outward and have a translucent fabric, contrasting the desert.
9. Jeddah Sports Hall
The project consists of a sports hall, a multi-purpose floor area of 7,500 square meters, which may be used as a single large playing field, and three separate handball courts. Stadium seating on both east and west sides for 5,000 spectators is provided in concrete stands under which, training and locker rooms and equipment storage are housed. A cafeteria and lobby are included in the program. The structural system consists of eight steel tube masts.

10. Intercontinental Hotel And Conference Centre
This 2000 seat conference center and 170-room hotel is a synthesis of advanced structural techniques and revived local artistic traditions that had become almost extinct. In their directness and simplicity, the vernacular details and finishes, such as the suspended wooden lattices, accent the machined elegance of the aluminum-clad conference center. The latter is structurally quite sophisticated, consisting of tent-like roofs suspended from steel masts. A small mosque, also shaded by a suspended lattice, is made of local basaltic stone. The jury commended this project by Frei Otto as “an effort to combine modern technology and functional forms in the context of Islamic culture.”

11. Mountain Tents For Hajj Pilgrims
The prototypic mountain tents are assembled on rocky, mountain slopes with inclines up to 35 degrees. The individual tent has a horizontal, artificial 4x4m plywood floor and is supported by a tubular aluminum framework standing on extendable legs. The aluminum framework forms a grid of two squares on each of the four walls. Canvas roofs form four-sided pyramids and serve as interior ceilings. The tent walls contain one door and a window that may be propped open for ventilation and viewing.

12. Artic City
Frei Otto’s proposal to house 40,000 people under a 2km dome in the Arctic Circle reflected the zeitgeist of the 1970s – a concern about the ecological future combined with the promise of a better tomorrow. The Arctic City would be sited on an estuary, with a harbor for shipping access and an airport on the outskirts. The city would be built in tandem with a nuclear power station, which would provide energy, as well as heating the air for the city and the water of the harbor to keep it perpetually ice-free.

13. Wilkhahn Furniture Factory
A set of four production pavilions with a light, tent-roof construction and suspended wooden beams was completed in 1987 to house the sewing and upholstery shops. The buildings appear to be more roof than anything else from the outside, but their sweeping curved tepee-like forms sit comfortably in the landscape and the interiors are welcoming and bright; wrapping, but not dwarfing the workers within in a comforting wooden cloak. The fact that the pavilions are set in a strict row, rather than huddled in the round as one might somehow expect, probably has functional reasons but adds a pleasing sense of the modular, which echoes the nature of their purpose.

14. TreeHouse
The purpose of the project was to create affordable housing while combining building and nature in an optimal way. Otto achieved this by planning a reinforced concrete infrastructure for the three buildings, while several architects, as well as the owners themselves, created their own designs for the eighteen individual units. This individual input gave the houses a “patchwork” quality within the supporting frame, allowing for a unified but diverse community. The houses were integrated with the site’s existing trees and other plants.

15. Interbau Main Exhibition Hall
The large pavilion of the exhibition “The city of Tomorrow” with an area of 52 x 100m was completely open with no external wall. A translucent roof covering with a simple solution made by wooden boards, steel pipes, and polystyrene-coated cotton canvas which is a watertight roof surface of 4,000 m2 was built with 79 buckles, traversed by long cross-valleys, over which the rain could flow. The roof skin was used primarily as a cover, but less as a self-supporting structure.
