St John's Co-Cathedral Museum

St John's Co-Cathedral in Valletta is a landmark of High Baroque architecture, built between 1572 and 1577 as the conventual church of the Knights of St John to designs by Maltese architect Girolamo Cassar. Its austere exterior gives no hint of what lies inside: every inch of the floor is covered with the marble tombstones of some 400 knights, while the barrel-vaulted ceiling carries a sweeping fresco cycle painted by Mattia Preti in the 1660s. The adjoining museum holds two paintings by Caravaggio, most notably the monumental 'Beheading of Saint John the Baptist' from 1608 — the only work the artist ever signed, reportedly in the blood of the Baptist. The oratory rooms containing the Caravaggios keep separate opening hours from the main cathedral, so visitors should verify access times and book tickets online in advance.