Equitable Building vs Aon Center

Comparing the Equitable Building and the Aon Center is interesting because they both rise in Chicago, IL, yet they were conceived by two different design teams, Skidmore, Owings & Merrill and Edward Durell Stone, and were completed at different points in time. They were finished more than 8 years 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 Aon Center is clearly the larger tower of the two, both in terms of height and number of floors. It rises to 1135ft (346m) with 83 floors above ground, while the Equitable Building reaches 456ft (139m) with 35 floors above ground.

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 Equitable Building and the Aon Center were designed in line with the aesthetic conventions of the International Style style.

The Aon Center was designed at a moment when the International Style style was already in decline, making it more of a lingering expression of the movement. In contrast, the Equitable Building was built when the style still carried greater cultural weight.

Both the Equitable Building and the Aon Center were designed to serve as commercial towers, and that has remained their main use since their completion, serving similar roles in the urban fabric.

The Aon Center also provides 679 parking spaces.

Both the Equitable Building and the Aon Center rely on a Framed Tube In Tube structural system.

A tube-in-tube system combines a reinforced central core with a perimeter of columns connected by floor slabs. This arrangement creates a stiff structure that resists both vertical and lateral forces efficiently.

They also employ the same type of facade, 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.