Fazlur Rahman Khan was a pioneer in the structural engineering of tall buildings. After buildings exceed sixty stories height, gravity loads account for a smaller proportion of structural weight than wind loads. Khan developed the tubed truss tower design to stiffen the building at taller heights without adding significant weight. The tube design had the added consequence of pushing the structure out to the exterior of the building to become part of its architectural expression. However, the acceptance of visible steel trusses was a slow process that parallels the acceptance of engineering infrastructure like bridges as aesthetic productions. This video traces a lineage of this process from Eiffel — who’s pylon designs look much like the Hancock Tower — to today.