The hip-roofed central section of this two-story structure of hard-pressed red brick, with a central tower originally topped with crenellations, is the original portion. Recessed wings, containing classrooms on the first floor and dormitory rooms on the second, were added in 1898–1899 and 1904–1905, bringing the total length of the rambling structure to 207 feet. In addition to classrooms and dormitories, the enlarged building contained library, gymnasium, cafeteria, and chapel. Old Main was threatened with demolition in 1949 and 1952 but was instead renovated and modernized. During the process, some of the original architectural details were lost.

Because of the constricted site and the growth of the institution, most new buildings have been built at a lower level, obscuring Old Main from easy view. The newer buildings form a motley collection. Among architects responsible for the disparate designs are Walter Martens, Alex Mahood, Warne, Tucker and Patteson, and Clint Bryan and Associates. Except for Mahood, from Bluefield, all were from Charleston, as was Old Main's architect, John Fulks.