The Jesuits' College was initially built in 1595 and underwent a major remodelling in 1647 after damage it sustained in the explosion of the nearby polverista. It is a three-storey building with an imposing façade on Merchants' Street. The building is arranged around a rectangular central courtyard, it has a number of cells on both floors, halls, the Aula Magna (Prime Hall), and a typical Maltese 17th century staircase.

The façade is comprised of a series of 10 windows on all floors emphasizing the sense of horizontality of this façade. The main entrance is accentuated by means of banded pilasters and a broken segmental pediment at the centre on which there is a statue of St Ignatius of Loyola.

At the back of the building, on St Paul Street, there is an early 19th century neo-classical doorway consisting of an architrave with an incised inscription in Greek, a frieze and a cornice supported by side pilasters attached to the wall and two Doric columns, set within a wide round-headed doorway. Only the upper half of the columns is deeply fluted.

The space between the entablature and the arched top of the door is a sculptured composition of the British Royal cypher consisting of the royal arms supported by the lion and the unicorn as a symbol of British Imperial propaganda.

Stone statues of the Virgin Mary and St Francis Xavier are also found on the corners of the building. These were donated in 1754 by Philip Wilhelm, Count of Nesselrode and Prior of Germany.

Mepa scheduled the Old University including the statues of St Ignatius of Loyola, the Virgin Mary and St Francis Xavier as Grade 1 national monuments as per Government Notice No. 276/08 in the Government Gazette dated March 28, 2008.