Architecture provides the background for most human activity, but buildings were very much in the foreground on Sept. 11, 2001. When the World Trade Center towers fell on live television that day, they were — and remain — the two tallest buildings to ever disappear from any city’s skyline. 

Immediately after, there was much speculation about whether we would continue to build tall buildings. That morning, Skidmore, Owings & Merrill design partner Adrian Smith was meeting with Donald Trump Jr. to review plans for a 2,000-foot-tall Trump Tower in Chicago. Not only did the client and architect scale back the building’s height based on the events in New York, but also, the drawings for that scheme were never publicly released. As completed in 2009, Donald Trump’s Chicago building is officially 1,389 feet tall, although that’s to the tip of its spire; its highest occupied floor is at 1,116 feet, which puts its perceived height at about the same level as the Aon Center and 875 North Michigan Avenue. 

The Chicago-based Council for Vertical Urbanism (CVU) is the arbiter of tall buildings throughout the world and has coined the term “supertall” for buildings between 300 and 599 meters in height (or 984 and 1,965 feet). On the morning of Sept. 11, 2001, there were just over two dozen buildings in the world that the CVU characterized as supertall, including five structures in Chicago: the Sears Tower, now known as Willis Tower, at 1,451 feet; the Aon Center at 1,136 feet; the John Hancock Center, now known as 875 North Michigan Avenue, at 1,128 feet; the AT&T Corporate Center, now known as the Franklin Center, at 1,007........

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