It is a marvel of engineering, sustaining the high winds in Chicago so well that the maximum wind draft at the top of the building is merely one foot. Its successful design consists of:<ref>http://www.pbs.org/wgbh/buildingbig/wonder/structure/sears_tower.html</ref> | It is a marvel of engineering, sustaining the high winds in Chicago so well that the maximum wind draft at the top of the building is merely one foot. Its successful design consists of:<ref>http://www.pbs.org/wgbh/buildingbig/wonder/structure/sears_tower.html</ref> |