Who knows what bundled tube construction is?
From the Chicago Architecture Foundation's website:
"a structural system for a tall building that uses giant square tubes, made up of individual columns, that provide stability again wind loads"
So you can tell from the photo that this was utilized in the construction of the Sears Tower. The brilliant engineer, Faziur Rahman Kahn, of Skidmore, Owings & Merrill developed this system to provide the building the necessary stability while meeting the client's space needs. More info here.
Chicago truly is the town of skyscraper history - the first one, the tallest, x-braced, - it all happened here first.
Sarah Rothschild, Realtor & Architectural History Nerd.