Today, Old Main serves as the administrative center of Penn State, housing the offices of the president and other officials.

Hugh McAllister designed the structure to contain classrooms, laboratories, offices, a chapel, and residential space for 400 students.

The limestone used to build the structure was quarried from the land directly in front of it, and was carried in part by a mule named Old Coaly, whose bones were subsequently preserved.

Between 1940 and 1949, Henry Varnum Poor utilized the fresco style to paint large murals (over 1300 ft2) on the second floor of Old Main that depict Penn State's land grant history.

For special events the tune can vary additionally; for example, on February 22, 2005, the university's 150th anniversary, the clock tower toned "Happy Birthday to You".

The frescoes located on the upper walls of Old Main’s lobby were created from the ideas of professors Harold Dickson, J.

Burn Helme and Francis E. Hyslop to pay a tribute to the university’s land grant education.