The building has a long porch outside, which is composed of thirty arches and it is divided into two floors, around a central courtyard with a double order of loggias.
Two large staircases lead to the upper floor which counts ten classrooms (that are not open to the public, as they are the main book stores of the Library) and two auditoriums at the ends of the building: one for the Artists (now the Reading Room of the Library) and the other one for the Legisti – law student (later called “Stabat Mater Room”).
On the ground floor some of the ancient premises are occupied by the Medical Surgical Society and the Academy of Agriculture.