Completed in 1900, it opened as the Administration (or Main) Building, housing many facets of University life, including academic and administrative offices, classrooms, the library, the chapel, a gymnasium, and even residence and dining facilities.

Built in the Romanesque style of southern France made popular by Henry Hobson Richardson (1838-1886), the administration building was a massive structure of native white limestone with two towers in front, a larger and taller square one with a steeple on the southwest corner and a smaller rounded one on the southeast corner

When completed the Main Building was said to be the finest educational structure in the South. The Main Building as it was called then, the Cullen Building today, transformed the image of Southwestern University in the minds of campus denizens and visitors.

When the Main Building was first built, the first floor was devoted almost wholly to the departments of physics and chemistry.

The Main Building’s auditorium has also served as a chapel and a gymnasium. In 2004, the auditorium was gutted and reconstructed to create a new space for the Alumni Center and the Center for Academic Success.

The Cullen Foundation gave the funds for the restoration of the Main Building in 1975-76.

One of the Cullen Building’s most intriguing elements is its tower, accessed by way of a spiral staircase from a third floor office. The unique tower room, with windows on all four sides, not only offers a bird’s eye view of campus and the region, but also features stone walls covered in signatures of former students dating back to the early 1900s.

The Cullen Building includes six classrooms, and the Offices of Alumni and Parent Relations, Human Resources, Business, Fiscal Affairs, Development, University Relations, Provost, and the President.