The parish originated in Byzantine times from the time of Emperor Theodosius I in the 4th century. The original church was the main Roman pagan temple of Gozo which had been converted by a Greek missionary into a Christian church dedicated to Saint George. The Roman temple stood at the site of the present church. The church is also documented in manuscript sources in c. 1250, when it is recorded functioning as a parish church. The foundation stone of the present church was laid on 7 August 1672. The church's construction was completed by in 1678 and it was consecrated on 21 September 1755 by Bishop Paul Alphéran de Bussan. At the time it was the largest Christian church on the island and was the first church in Gozo to be built in the form of a Latin cross. In the 1930s the church was enlarged with the addition of the naves and the side chapels. Between 1939 and 1940 the dome of the church was reconstructed due to damage done in the earthquakes of 1693 and 1789. The roof was also rebuilt and reconstructed in the Roman style arch between 1938 and 1939. The basilica has a total of 11 side chapels. The door, named Porta Salutis, is made entirely of bronze and was manufactured in Verona on a design by John Grima