Buildings of historic importance include St John's Co-Cathedral, formerly the Conventual Church of the Knights of Malta. It has the only signed work and largest painting by Michelangelo Merisi da Caravaggio. The Auberge de Castille et Leon, formerly the official seat of the Knights of Malta of the Langue of Castille, Léon and Portugal, is now the office of the Prime Minister of Malta. The Grandmaster's Palace, built between 1571 and 1574 and formerly the seat of the Grand Master of the Knights of Malta, used to house the Maltese Parliament, now situated in a purpose-built structure at the entrance to the city, and now houses the offices of the President of Malta.