Located on three redeveloped blocks in downtown Columbus, Indiana, the headquarters accommodates 1,000 employees and is arranged around an existing historic nineteenth century mill building. Tree-shaded surface parking for 700 cars is located across the street and behind the complex. A late-19th century cereal mill had occupied a portion of the site. The mill remains and is the centerpiece of a park that encompasses the headquarters. The mill building is used as an employee cafeteria and training center.

The building is a one-story structure occupying the entire site. A narrow, two-level spine containing enclosed offices and conference rooms borders the high, open-office work area. Windows and mirrored spandrels enhance the feeling of spaciousness. Skylights are designed to provide a warm, natural illumination, without the harsh shadows of direct sunlight. The structure is composed of poured-in-place concrete columns supporting precast concrete wall components. The roof is steel and concrete, with an arched ceiling of fabric-covered acoustical panels.

The main building contains workstations in a series of interlocking high spaces. Conference rooms run in a narrow band through the length of the building. The work space, flanking heavily trafficked streets, has three narrow bands of ribbon windows, each one-foot high, to eliminate problems of noise and sun control. To give a greater feeling of spaciousness, the precast spandrels between the windows are clad in mirror; looking at these walls one sees either beyond to the outside, or beyond to the inside. This interlocking visual system is reversed to take advantage of the landscaped park on the north side. There the narrow windows become beams, and the beams wide windows.

An arcade of columns connects the two embracing ends of the main structure and establishes both the continuity of the street line and the containing wall of the public garden. The strong exterior column expression relates to the portico of the adjacent Post Office Building; and the materials, enclosed garden, and pool also relate to one of the earliest modern buildings built in Columbus - the Tabernacle Church of Christ designed by Eliel Saarinen in 1940, which is located on the other side of the business district. The corner of the building nearest the center of the City is cut away to provide a visitor's entrance and also to recognize the small park across the street, which is an integral part of the expanded Irwin Union Bank and Trust Company.