Pioneer Architect of the Week Frei Otto (1925 - 2015) Frei Paul Otto was a German architect and structural engineer known for his use of lightweight structures, in particular tensile and membrane structures. He won the RIBA Royal Gold Medal in 2006 and the Pritzker Architecture Prize in 2015. He founded the Institute for Lightweight Structures at the University of Stuttgart and was head of the department from 1964 to his retirement. Otto tried new methods to reduce material and energy use to cre