Complex sentence: Frei Paul Otto (31 May 1925--9 March 2015) was a German architect and structural engineer noted for his use of lightweight structures, in particular tensile and membrane structures, including the roof of the Olympic Stadium in Munich for the 1972 Summer Olympics.
Split into simpler sentences: Frei Paul Otto (31 May 1925--9 March 2015) was a German architect and structural engineer. He designed the roof of the Olympic Stadium in Munich which was created for the 1972 Summer Olympics.