A depiction of his most important works New forms of lightweight and adaptable construction Insight into interdisciplinary research projects Frei Otto's work as a source of inspiration for architects and engineers worldwide No other architect provided as many ideas and inspiration to construction in the second half of the 20th century as Frei Otto. Lord Norman Foster described this great pioneer of lightweight construction simply as 'an inspiration'. Frei Otto explored the foundations of resource and energy-efficient building well before these issues received the attention of the wider public. By including users in construction planning and taking into account local and climatic conditions, he opened new avenues for the building industry. To celebrate his 90th birthday, the publication provides insights on the key aspects of his work. At its heart was the search for natural designs and an exploration of form-finding and self-development processes. As such he created a whole universe of ideas using membrane, net and convertible roofs with umbrellas, grid shells, and pneumatic structures. The book introduces his key works and highlights how his ideas were adopted and continued throughout the world.