800 W. Fulton Market
800 W. Fulton market embraces a visual set of steel braces along the east and west façades of the building. K’Von Jackson for WBEZ

What’s That Building? 800 W. Fulton Market

During the rotation of the seasons, the building’s metal exoskeleton will get looser and tighter, then back again — looking slightly different in the hot and cold months.

800 W. Fulton market embraces a visual set of steel braces along the east and west façades of the building. K’Von Jackson for WBEZ
800 W. Fulton Market
800 W. Fulton market embraces a visual set of steel braces along the east and west façades of the building. K’Von Jackson for WBEZ

What’s That Building? 800 W. Fulton Market

During the rotation of the seasons, the building’s metal exoskeleton will get looser and tighter, then back again — looking slightly different in the hot and cold months.

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In the year since opening, a Fulton Market building has become known for the metal exoskeleton that runs up its east and west sides. The braces, which climb 19 stories, are misshapen Xes that look like shoelaces that haven’t been pulled tight.

The Xes are, of course, not too loose and they do the job. During the rotation of the seasons, those braces will get looser and tighter. The center of each high-waisted X in those braces will move within a range of 9 inches, according to Skidmore, Owings & Merrill (SOM), the architecture firm that designed 800 W. Fulton Market.

If you stood in front of the building’s main entrance on Green Street and pointed your camera straight up on a hot day when the braces have expanded, you would get a different image than if you did so on a cold day when they’ve contracted.

The braces are known informally as “Baker braces,” after Bill Baker, a structural engineer at SOM with a long history of innovations. Baker’s engineering is in the Burj Khalifa in Dubai, the world’s tallest building at 163 stories. Baker first used the high-waisted Xes at 100 Mount St., a 35-story tower in downtown Sydney, Australia, that was completed in 2019.

steel beams on 800 W. Fulton Market
The building’s steel beams protrude a few feet from the side of the structure. K’Von Jackson for WBEZ

The braces aren’t there only as visual catnip for Instagrammers. They make the architectural concept of the building work, said Julie Michiels, a design director at SOM who led the interior work.

Because much of the historical low-rise architecture immediately south of the site and elsewhere in Fulton Market is brick, the design team wanted a mostly brick exterior to attract commercial tenants who prefer wide open floor plans, and wanted to get away from building with a central core. So they set the core to the north and used the braces to lace the brick walls together.

18th-floor terrace of 800 W. Fulton Market
The eighteenth floor terrace offers extended views of the skyline and the city’s West Side. K’Von Jackson for WBEZ

“The braces basically pull the wings and keep the building from any side-to-side motion,” Michiels said.

One result of moving the core to the north side is a broad, airy common area at the base that is much more than a lobby. The area has a partial second level cantilevered over the ground level so it seems to float in the middle of the three-story space.

800 W. Fulton Market lobby
The lobby displays inlaid marble and greenery, along with a floating mezzanine open to the public. K’Von Jackson for WBEZ

This multi-level space brings another key visual feature of the building’s exterior to the indoors. South of the site are low-rise buildings, and north are high rises. SOM envisioned this building as bridging those two scales, with the south side having a staircase look that rises up from the lower to the taller buildings, Michiels said. Each step has a green landscaped space on its roof, another element that carries through to the enlarged lobby.

Another result of moving the core to the side is that some of the elevators are now daylit because they’re next to the north exterior wall, which is glass. As you ride up inside the building “you’re still in touch with the outdoors,” Michiel said, a very different experience from riding up in an enclosed box with artificial lighting.

eighth-floor conference room in 800 W. Fulton Market
An eighth-floor conference room views the cross beams from inside, reminiscent of urban architecture. K’Von Jackson for WBEZ

The building at 800 W. Fulton is sui generis, its own thing, but in a couple of key ways it nods to the history of SOM in Chicago. The core pushed to the side is also seen in the firm’s Inland Steel building, finished in 1958, and those external braces would remind even the most casual Chicago architecture fan of the former John Hancock Center, now known as 876 N. Michigan, completed in 1970.

Dennis Rodkin is the residential real estate reporter for Crain’s Chicago Business and Reset’s “What’s That Building?” contributor. Follow him @Dennis_Rodkin.

K’Von Jackson is the freelance photojournalist for Reset’s “What’s That Building?” Follow him @true_chicago.