7 South Dearborn represents a major advancement
in the engineering of tall buildings. Although taller than the
Sears Tower, the building's floor plates are substantially smaller.
This is a result of its stayed mast structural system, formed
from a series of spaces that evolve from a reinforced concrete
core. A limited number of widely spaced columns dot the perimeter
of the office component, and the interior is column-free. The
cantilevering of the upper 57 residential floors from a concrete
core makes columns unnecessary on the exterior walls and provides
11-foot uninterrupted views in all directions.
