The Sacrestia Maior is attached to the back of the basilica: it is the main hall of the sacristy, where the priests vest for the celebration of the liturgy. The ceiling of this hall was decorated between 2000 and 2003 by Gozitan painter Paul Camilleri Cauchi. The three canvases represent three stages in the Christian history of the island of Gozo. The first one from inside depicts the Christianisation of the island, the second one the rebuilding of the parish of Gozo in 1672, and the third one the veneration of St George as Patron of Gozo. A niche in this sacristy hosts the statue of St Joseph, represented here as Patron of the Universal Church; the work, in papier-mâché, was made by renowned Gozitan artist Wistin Camilleri in 1924.

The other halls which form part of the basilica complex serve as venues for several pastoral and cultural events during the year. The Aula Mgr Giuseppe Farrugia with its Grand Yamaha Concert Piano and 1785 Antunes harpsichord, and St Michael’s Hall with its nineteenth-century British pipe organ, host concerts all year round. The Aula Capitularis in the first floor is the official seat of the Collegiate Chapter and houses various precious paintings, some of which were the original altarpieces in the basilica. Many of these works of art are now being restored and form part of the collection in Il-Ħaġar, the EU co-funded museum built by the Fondazzjoni Belt Victoria. The treasury and archives of the basilica contain a rich collection of manuscripts, statuary, paintings, silverware and sacred vestments, together with many other valuable objets d’art. The parish centre was built in the late 1970s by Archpriest Emanuel Mercieca, and an extension including a new house for the clergy was added on the initiative of Archpriest Mgr Ġużeppi Farrugia between 1999 and 2005.