The tallest building in North America provides an unrivaled view of a cityscape, all from the comfort of being suspended 1,353 feet in the air. The Sears Tower 'Ledge' has walls, floors, and ceilings made of glass, jutting out from the building to give visitors a unique and vertigo worthy view of Chicago's architectural landscape.
The Sears Tower is the third tallest building in the world; 110 stories constitute 1,450 feet, making it the tallest building in the Western Hemisphere. The glass boxes, termed 'the Ledges', were opened to the public July 2, 2009. Four 10 foot by 10 foot compartments protrude 4.3 feet from the building's 103rd floor observation room, the Skydeck.
With three layers of glass totaling one and a half inches thick, each platform can support up to 5 tons. A completely transparent three sides, top, and bottom designed to generate the sensation of hovering over Chicago do just that, as the box extends far enough for one row of visitors to stand suspended at a time. A clear day presents a view of up to 50 miles and four states.
Structural glass design experts of Halcrow Yolles took the original architectural plans (firm Skidmore, Owings and Merril) a step further, from the concept of devising a retractable structure for easy cleaning, to detailing each box to have near-invisible structural support. All the side and bottom perimeter steel was removed, completing the floating on air appearance.
The idea for the Ledges supposedly originated from the constant cleaning workers had to do on the Skydeck's windows. Tourists every day would press their foreheads against the glass, attempting to peer down at the city, leaving smudges that were becoming tiring to clean. Now the staff will need to clean the occasional footprint left by fearless children, or handprints from nervous guests ensuring the walls are still there.
Other changes for the Sears Tower includes a name change to the Willis Towers, gone into effect the summer of 2009. Additionally, officials announced a $350 million 5-year green renovation plan that includes the installation of wind turbines, roof gardens, and solar panels.