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Built in 1956, the Interstate Building originally had only 3 stories; the fourth floor was added in 1962. This is a prime example of the mix of both the Modern Movement (steel, glass, and reinforced concrete) and International Style (low profile and horizontal window bands).

The building was considered an “addition” to the Interstate Power Company located directly across the alley on Main Street. The original purpose was to house the early and extremely large computers (the initial computer used took up the entire ground floor), as well as the air conditioner, which kept the large computer and system from melting itself.

With time, the Interstate Building transformed into the office building for employees of the company and remained that way until 1996, when Alliant Energy purchased and absorbed the Interstate Power Company.

Completion Date: 2007

Size: 25,000 Total SF

Location: Dubuque, IA

Type of Project: Office

Gronen Responsibility: Developer, Contractor, Project Manager

Total Development Cost: $3.2 million

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