Light court and stair by Frank Lloyd Wright: vertical view of the space, looking towards the iron stair; By mixing modern building techniques such as metal framing, fireproofing, elevators and plate glass, together with traditional ones such as brick facades and elaborate ornamentation, Burnham and Root sought to create a bold architectural statement that would nonetheless survive as a commercially successful office building. Of particular note was a "floating" foundation - a reinforced concrete slab that provided the building's weight with a solid platform atop Chicago's notoriously swampy soil. The term for the type of foundation that Root designed is grillage foundation, a foundation where iron rails and the structural beams are combined...