Inland Steel Building vs Aon Center

Comparing the Inland Steel 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 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 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 Inland Steel Building reaches 331ft (101m) with 19 floors above ground.

Aon Center also offers more total built-up area, a total fo 3,599,965 sqf (334,448m²), which is about 3,274,970 sqf (304,255m²) more than what the Inland Steel Building offers.

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 Inland Steel 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 Inland Steel Building was built when the style still carried greater cultural weight.

Both the Inland Steel 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.

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

The Inland Steel Building 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.