Hillyer Hall is a two-story, wood-frame structure, converted from a gymnasium/multipurpose facility into a bookstore and post office in 1958. The exterior of the building is clad in wood shingles and the roof gable ends repeat the gothic motif of the nearby granite buildings. The Black Box Theater contains a 2,500 SF flexible theater space in the former gymnasium on the upper level. The former stage provides space for a set-building shop. Ground-floor space provides green room space and an entrance lobby. New main staircase and elevator towers, bringing the facility up to code, complement the style of the original structure.