[1] The Old Main building is four-stories high with a stucco and Wissahickon schist stone exterior.

The discrepancy in the measurements is the result of renovations that were made to the structure in 1883 following a fire that destroyed the upper floors on the eastern end.

The symmetry of the building was lost with the eastern addition of an auditorium, classrooms and dormitory space.

It was built in order to separate dangerous laboratory conditions from the dormitory area of the Old Main building.

After expansion of the school and construction of additional facilities, Old Main was used as the center of administrative services for the College.