Three Illinois Center vs Aon Center

Comparing the Three Illinois Center and the Aon Center is interesting because they both rise in Chicago, IL, yet they were conceived by two different design teams, Fujikawa Conterato Lohan and Associates and Edward Durell Stone, and were completed at different points in time. They were finished more than 6 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 Three Illinois Center reaches 351ft (107m) with 28 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 Three Illinois Center and the Aon Center were designed in line with the aesthetic conventions of the International Style style.

Both buildings were completed when the International Style style was already past its peak. This makes them feel like late echoes of the movement, more reflective of continuity or nostalgia than of cutting-edge design at the time.

Both the Three Illinois Center 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.

Both towers provide significant parking capacity, with Three Illinois Center offering 294 spaces and the Aon Center offering 679.

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

The Three Illinois Center uses a Frame structural system, which relies on a regular grid of columns and beams to sustain its weight, while the Aon Center uses a Framed Tube In Tube system, that combines a strong central core with a perimeter tube of columns.

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.