St. John's Co-Cathedral is Malta's most prized monument to the glorious epoch of the Knights of St. John. It was originally the Conventual Church of the Order, the focus of religious ritual and obedient service dedicated to St. John, who is patron saint of the Order. In St. John’s Square, the surrounding space allows a full view of its somewhat austere façade giving the impression of strength and solidity, of a forthright and noble purpose.
For more than 70 years after its completion, St. John’s remained a vast stone structure barren of decoration. In 1661, Grand Master Rafael Cottoner commissioned Mattia Preti, one of the most outstanding artists of the Italian Seicento, to decorate the ceiling and redesign the interior.
Once within the portals there is the overwhelming surprise of high Baroque, a starling contrast to the somber exterior. It’s a blaze of colour and a cornucopia of decoration where every inch of the stone walls, arches and columns are carved into an embroidered medley of flowers, scrolls, shells, angels, symbols and heraldic emblems, gilded and coloured. The floor is paved with marble slabs, each with a tomb of a Knight bearing his coat of arms in intricate inlay. The crypt beneath the Cathedral contains the tombs of de L’Isle Adam, the Grand Master who brought the Knights to Malta, and De La Valette who led them through the Great Siege of 1565.
Despite richness everywhere, the eye is directed to the high altar, where Preti’s frescoed vault depicts the history of the Knights. In the Oratory is Caravaggio’s masterpiece 'The Beheading of St. John' which one renowned art critic has described as the painting of the 17th century.
The adjacent museum relates solely to the history of St. John’s when it was the conventual church of the Order, It contains silver, sacred church vestments and beautiful scripted and illustrated choral books. Most of the treasury’s priceless riches were plundered by Napoleon’s troops in 1798. Fortunately the unique collection of Flemish tapestries was spared. There are 14 pieces, all in mint condition which were the gift of Grand Master Ramon Perellos at the beginning of the 18th century.
Stiletto heels and narrow heeled shoes are not permitted on the inlaid marble floor of St John’s cathedral.