Union Bank Plaza Tower vs Aon Center

Comparing the Union Bank Plaza Tower and the Aon Center is interesting because they both stand in Los Angeles, CA, and were completed within 5 years of each other, but they were designed by different architects.

This offers a unique glimpse at how rival designers approached projects in the same city during the same era.

The Aon Center is clearly the larger tower of the two, both in terms of height and number of floors. It rises to 858ft (261.5m) with 62 floors above ground, while the Union Bank Plaza Tower reaches 515ft (157m) with 40 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 Union Bank Plaza Tower 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 Union Bank Plaza Tower was built when the style still carried greater cultural weight.

Both the Union Bank Plaza Tower 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 Union Bank Plaza Tower offering 914 spaces and the Aon Center offering 1028.

Both towers share the same structural solution, a Frame system.

A frame structure uses a grid of columns and beams to carry the building's loads. This frees the walls from structural duties, allowing for flexible floor plans and larger windows.

However, when it comes to the facade, both buildings use different approaches. The Union Bank Plaza Tower uses a Window Wall facade, while the Aon Center uses a Curtain Wall facade.

A Window Wall facade like the one seen in the Union Bank Plaza Tower uses panels fitted between floor slabs, leaving slab edges visible, while a curtain-wall facade like the one seen in the Aon Center uses a lightweight glass curtain wall hung from the structure.