Until his death , Otto remained active as an architect and engineer , and as consultant to his protégé Mahmoud Bodo Rasch for a number of projects in the Middle East . One of his more recent projects was his work with Shigeru Ban on the Japanese Pavilion at Expo 2000 with a roof structure made entirely of paper , and together with SL Rasch GmbH Special and Lightweight Structures he designed a convertible roof for the Venezuelan Pavilion . In an effort to memorialise the September 11 attacks and its victims as early as 2002 , Otto envisioned the two footprints of the World Trade Center buildings covered with water and surrounded by trees ; his plan includes a world map embedded in the park with countries at war marked with lights and a continuously updated board announcing the number of people killed in war from 11 September 2001 , onward
September 11 attacks
September 11 attacks
Frei Otto