St John's Co-Cathedral

Built by the Knights of St John between 1573 and 1578, St John's Co-Cathedral is one of the most extraordinary baroque interiors in Europe — and that's not hyperbole, it's just the consensus of everyone who walks through the door. From the outside it's deliberately plain, a fortress-like facade that gives away almost nothing. Then you step inside and the effect is genuinely staggering: every inch of the vaulted ceiling painted by Mattia Preti, the floor a mosaic of 400 marble tombstones belonging to Knights from across Europe, gilded side chapels dedicated to each of the Order's langues, or national groupings. The Knights of St John were a military-religious order who ruled Malta for 268 years and poured their wealth and prestige into this church. It shows.

The main event most visitors come for is the Oratory, which houses Caravaggio's 'The Beheading of John the Baptist' — the largest canvas he ever painted, and the only work he signed with his name (written in the blood of the Baptist). Caravaggio spent time in Malta in 1607–1608 and also painted 'St Jerome Writing,' which hangs in the same room. Standing in front of these two works, in the actual place they were made for, is a genuinely moving experience. Beyond the Oratory, it's worth taking time with the individual chapels — each has distinct artwork and character — and with the Cathedral Museum, which holds illuminated manuscripts, Flemish tapestries, and Knights' vestments.

The co-cathedral is closed on Sundays for religious services, which means visiting is a weekday or Saturday affair. Entry is ticketed, and the audio guide is worth the small extra cost — it makes the floor tombstones and chapel histories legible rather than just decorative. Arrive early in the morning to beat the cruise ship groups, which tend to flood in mid-morning. Shoulders and knees must be covered, and while scarves and wraps are sometimes available at the door, bringing your own is safer.