St John's Co-Cathedral

From the street, St John's looks like a fortress church, which is what the Knights of St John built. Inside, every surface is carved, gilded and painted: the vault frescoed by Mattia Preti, the walls worked into gold-leaf stone, and the floor made of nearly four hundred inlaid marble tombstones covering the knights buried beneath. The oratory holds the reason many people come - Caravaggio's Beheading of St John the Baptist, the largest canvas he ever painted and the only work he signed, made while he was himself a knight on the island, alongside his St Jerome Writing.

What you actually see

• The nave and vault - Preti's frescoes and the gilded stone carving.
• The marble tomb floor - hundreds of inlaid knights' tombstones.
• Caravaggio's Beheading of St John - his largest and only signed painting.
• The chapels of the langues - each national section of the Order, richly decorated.

When to go

Open year round and a perfect indoor stop in summer heat or winter rain. Mornings are quieter; cruise-ship days fill it. It closes to visitors on Sundays and public holidays for services, which catches people out.

Honest expectations

Stiletto heels are banned to protect the marble tomb floor, and the dress code covering shoulders and knees is enforced. Photography rules are strict in the oratory with the Caravaggios and no flash anywhere. Timed entry and queues are common in season - booking online saves standing outside. It is not large, but rushing it wastes the ticket; the audio guide is genuinely good.

Nearby

The Grandmaster's Palace, Upper Barrakka Gardens and the Valletta waterfront.