Innovation: John Hancock Center
Location: Chicago, Illnois
By: Skidmore, Owings, and Merrill
The John Hancock Center, a 100 story structural expressionist skyscraper by Skidmore, Owings, and Merrill was one of structural engineer Fazlur Khan’s first buildings to exhibit much of the structural systems found in many of today’s modern skyscrapers.  Khan’s understanding of structural systems would allow engineers to create buildings that reached heights few could dream of. During the time of the construction of the John Hancock Center, 20 story buildings were still noteworthy, but Khan’s Tube Structural Systems would allow buildings to reduce the lateral loads such as wind and seismic forces that kept buildings low to the ground, while significantly reducing the amount of steel needed per square foot. His system accomplished this by utilizing the exterior wall perimeter of the structure as thin walled tube. Khan’s X-bracing added to the structural integrity by directing forces to the exterior columns, eliminating the need for interior columns. 
The John Hancock Center not only gave engineers the tools to create modern skyscrapers, which rely on their ultra light weight design to allow them to top out at incredible heights, but also stands as a terrific example of structural systems presented in an exterior aesthetic form. Other later buildings such as the Llyod’s Building do this quite well.
Innovation: Computer Aided Design (CAD)
Location: Cambridge, Massachusetts
By: Ivan Sutherland
Computer Aided Design combines computer graphics with application software to enable users to create, modify, analyze and optimize designs. CAD is used in classrooms and businesses worldwide and has advanced greatly since its beginning in 1961. Ivan Sutherland of Massachussets Instiute of Technology created the first CAD program, Sketchpad, with inspiration from Servo Mechanisms Laboratory numerical control. As programming and research developed in the 70’s and 80’s CAD moved beyond 2D and 3D drafting to include more engineering application features. Today’s CAD has become a very accessible product that allows users to work from personal computers to quickly and efficiently create designs in a number of different industries.
Today’s CAD user most likely uses software systems such as AutoCad for 2D drawing and modeling. More powerful programs such as Pro-E for design and ANSYS for structures allow for much more complex analysis.
Innovation: Palmira Chapel
Location: Cuernavaca, Mexico
By: Felix Candela
The chapel highlights Felix Candela’s astute understanding of structural design, geometric concepts, and clean architecture aesthetics. The chapel’s structure takes the form of a hyperbolic paraboloid which allows for compression and tension forces to act on particular areas of the structure . The surfaces are anticlastic, meaning that the principal curvatures of the form have opposite signs at any given point, which reduces shear forces and bending.  This reduction in bending allows for dramatically reduced materials, in this case, concrete. Thin shell concrete roofs can be as thin as 5/8 inches wide, and do not rely on interior columns or buttresses for support. In fact, thin shell concrete structures are very strong, and are particularly excellent at withstanding earthquakes.
Candela’s work with thin shell concrete paved the way for many famous structures such as the TWA Flight Center and the Sydney Opera House which blend architectural aesthetics with engineering innovation.
Location: Black Mountain College, North Carolina
By: R. Buckminster Fuller
R. Buckminster Fuller began working with the concept of Tensegrity in 1948 while he was teaching at Black Mountain College in North Carolina. He would attract the attention of an artist Kenneth Snelson who created seemingly floating sculptures, but Fuller would not coin the term Tensegrity, or “Tensional Integrity” until 1955 . Tensegrity is defined as a structural principle involving isolated components of compressing surrounded by a net of continuous tension that the compressional members do not touch and the tensioned members outline the structure. Because of this design structural members will not exhibit a bending moment. Tensile forces exert themselves over the most direct path between two points and since members in Tensegrity are positioned at these paths, the members are incredibly strong despite their small mass and cross sections.
In the mid 1900’s Fuller and Snelson became famous for their structures that exhibited Tensegrity, including Fuller’s Montreal Biosphere and Snelson’s sculpture, Soft Landing. Other architectural works such as the Kurilpa Bridge in Brisbane, Australia use the principle of Tensegrity. The principle is also exhibited in biology and chemistry.