St John’s Co-Cathedral is a combination of Baroque art and architecture and was built for the Knights of St John. The Grand Masters and many knights donated treasures of high artistic worth in order to enrich the cathedral. Nowadays it is also used for cultural events. One of the most striking paintings found in this Cathedral is the distinctive Caravaggio painting depicted the beheading of St John. Something very the extraordinary is the paving made up of 300 marble tomb slabs along the domed central nave with frescoes of Mattia Preti.