71 South Wacker Building vs BMO Tower

Comparing the 71 South Wacker Building and the BMO Tower is interesting because they both rise in Chicago, IL, yet they were conceived by two different design teams, Pei Cobb Freed & Partners and Goettsch Partners , and were completed at different points in time. They were finished more than a decade apart.

This contrast within the same city allows us to see how different creative minds interpreted the evolving needs of Chicago across time.

Let's take a closer look!

The BMO Tower is clearly the larger tower of the two, both in terms of height and number of floors. It rises to 728ft (222m) with 51 floors above ground, while the 71 South Wacker Building reaches 679ft (207.1m) with 48 floors above ground.

Despite being taller and having more floors, BMO Tower has less total built-up area than 71 South Wacker Building.

Of course, each project may have faced different briefs or regulatory constraints, which we don't really know about and could also explain the outcome.

Both the 71 South Wacker Building and the BMO Tower were designed in line with the aesthetic conventions of the Contemporary style.

At the time, this style was at the height of its popularity. So both Pei Cobb Freed & Partners and Goettsch Partners followed what was in many ways expected of them, producing designs that fit comfortably within contemporary architectural norms, rather than breaking with convention.

Both the 71 South Wacker Building and the BMO Tower were designed to serve as commercial towers, and that has remained their main use since their completion, serving similar roles in the urban fabric.

Both towers provide significant parking capacity, with 71 South Wacker Building offering 163 spaces and the BMO Tower offering 324.

The two towers rely on different structural systems, reflecting distinct engineering strategies.

The 71 South Wacker Building uses a Framed Tube In Tube structural system, which combines a strong central core with a perimeter tube of columns, while the BMO Tower uses a Frame system, that relies on a regular grid of columns and beams to sustain its weight.

Yet, when it comes to their facade, they both employed the same solution, a Curtain Wall facade.

A curtain wall is a non-load-bearing facade hung from the structural frame. It is anchored to floor slabs and transfers only its own weight and wind loads, allowing for sleek, glassy exteriors.