To aid in occupant comfort, belt trusses were rigged on the upper mechanical floors thereby further reducing shear forces (i.e. It allowed for large open office spaces on the lower levels, where Sears, Roebuck and Company would reside, and smaller floor plates on the upper levels with unobstructed views of the cityscape. This 'bundled-tube' configuration was a revolutionary engineering concept at the time, pioneered by SOM's very own Fazlur R. as implemented in the World Trade Center towers.) This is in contrast to the popular tube-in-tube system, in which a rigid network of floor diaphrams and closely-spaced exterior columns work in unison to resist lateral loads whereas a centralized core functions to carry vertical loads exclusively (e.g. Each tube is a rigid steel frame that performs in tandem with its neighbor to efficiently counteract all lateral and gravity loads. The superstructure consists of nine interlocking tubes that terminate at different heights, creating the iconic stepped-back appearance of the tower. Sears Tower was the last supertall building constructed during the International architecture period, and SOM's interpretation of the style is remarkably bold and awe-inspiring. Much like the Empire State Building, the colors typically coincide with national events and holidays.

By the fall of 1995, a seasonal rooftop illumination program was also initiated. This also included the construction of two glass-and-steel canopies over the Franklin Street and Jackson Street entrances. Following Sears' departure, the building underwent a comprehensive renovation by DeStefano + Assoc of all public and Skydeck lobbies and elevators. In 1984, SOM was commissioned to overhaul many of the tower's lower-levels, including the addition of a vaulted atrium alongside Wacker Drive. Both were surpassed within their first year of completion by Sears Tower, which opened its doors on September 10, 1973. Originally designed in the late 60's by Bruce Graham of Skidmore, Owings, and Merrill for Chicago-based Sears, Roebuck and Co, Sears Tower was officially topped out on May 3, 1973.ĭuring the skyscraper's initial construction, which began in August of 1970, two other prominent office tower projects vied for the 'world's tallest' title: the Standard Oil of Indiana Building (now the Aon Center) located in downtown Chicago and the World Trade Center high-rise complex formerly located in Manhattan.

Sears tower ticket price