What was once a castle and royal residence is now one of the largest art museums in the world. Located in the heart of Paris, the Louvre Museum houses some of the most impressive works of art in history, including 'the Venus de Milo', 'the Winged Victory of Samothrace', and Leonardo Da Vinci’s 'Mona Lisa'. Open every day from 9 AM to 6 PM, except on Tuesdays, the museum is definitely worth a visit. But, considering the fact that it is the world’s most-visited museum, it is a good idea to buy tickets in advance.