By the early 1800s the original parish church in Mosta designed by Tumas Dingli became too small for the ever-growing population of parishioners. Giorgio Grongnet de Vasse was commissioned to design a new church of monumental proportions, heavily inspired by the Roman Pantheon in Rome, to which Grongnet added a pair of belfries. He convinced the local parish priest to accept his unusual proposal, however, Grongnet came up against strong opposition led by Bishop Caruana, who instead favoured a design prepared by another architect. Despite the criticism, Grongnet prevailed.

The Rotunda church may not be a true inspiration of neo-classical architecture, but it has emerged over time as a landmark building and a Maltese icon. It broke away from the traditional Latin Cross layout and also consists of an eclectic mix of architectural motifs and experimentation with proportions, some oversized.

No account of the famous church would be complete without citing an incident that occurred during World War II. In April 1942, during an aerial bombing, it is said the Rotunda suffered a direct hit as a 200kg German bomb punctured through the dome and landed within the church interior without exploding. The structural integrity of Grongnet’s dome remained intact.

The Malta Environment and Planning Authority scheduled the parish church as a Grade 1 monument on August 26 as per Government Notice 782.