The 150 North Riverside site is located prominently at the confluence of the three branches of the Chicago River and less than one block away from one of Chicago's busiest commuter train stations. With exposed railroad tracks on the west side of the site and the city requirement for a public right-of-way on the east side, the remaining area on which to build was considered impossibly narrow, and the site sat undeveloped for decades.

Utilizing a unique core-supported structure with a very small footprint at grade, the design resolves the site challenges and provides a Class A office tower with efficient, column-free floor plates. The building’s unusual core-supported design results in a 221-meter tower resting atop a base that is merely 12 meters wide. The building is most noticeably significant for the narrow aspect ratio of its core; at 20:1 it is among the world’s thinnest. In consideration of this, the building also contains the first-ever application of a 12-tank tuned liquid mass damper (TLMD) at the tower’s top to manage both building drift and acceleration. With a total of 605,665 liters of water, the TLMD also provides city-approved fire protection storage tanks to supply the building’s sprinkler system, a creative dual purpose that is a Chicago first. The 16 sloping columns at the cantilevers feature the largest rolled-steel shapes ever used in a high-rise building in the U.S. The shapes are 1,092 millimeters deep and weigh 1,377 kilograms per meter.

This narrow building footprint accomplishes several strategic goals, in addition to facilitating column-free office space. It also creates a dramatic interior space in the lobby, while allowing for more than 75 percent of the property to be unenclosed outdoor space. The tower’s limited footprint and the angled sweep of its underside appear to usher the river past the site, breaking down the tower’s considerable mass and presenting a balanced composition.

Tenants and visitors enter through a dramatic, 27-meter-high lobby enclosed by a glass-fin wall hung from the structure above. The lobby features the “150 Media Stream,” a one-of-a-kind curated multimedia wall that showcases the work of local and other digital artists. The 46-meter-long, site-specific installation provides a lobby focal point while also addressing the transition between the opaque wall over the parking deck and the glass-fin wall above, using 89 LED blades, carefully choreographed in varying lengths and widths.

Building amenity spaces include a restaurant, bar, fitness center and conference center – all with water views. The condensed lobby and elevator cores open the majority of the 8,093-square-meter site as a landscaped public park, plaza and riverfront promenade.

Outside, the park and plaza provide more than 300 linear meters of seating, multiple assembly/event spaces and 110 meters of at-grade Riverwalk frontage, which has already become one of the most populated walkways for downtown commuters. Those who negotiate the grade change of the landscaped plaza on the west side of the tower find themselves in the unique position of being outdoors and at eye level with Chicago’s famous elevated train, without being in a station.
The structural acrobatics performance has paid off commercially as well as urbanistically, taking what was once deemed an unbuildable site and creating an optimal mix of leasable floor space, public outdoor space, and semi-public indoor space, complemented by custom-designed artwork.