On the first Sunday of the month, bucket-list museums such as The Louvre, the Musée d'Orsay, Musée Rodin, Centre Pompidou and Musée Picasso open their doors to art buffs for zilch. Brace for longer lines and less room to move, of course, but revel in the fact you’ll see the greats (including da Vinci’s Mona Lisa, and Van Gogh’s Starry Night) without having to whip out your wallet.