With its Great Gallery stunningly refurbished in 2014, there's even more reason to visit this exquisite gem of an art gallery—although housing one of the world's finest collections of old master paintings is reason enough. This glorious collection and the 18th-century mansion in which it's located were bequeathed to the nation by the widow of Sir Richard Wallace (1818–90). Wallace's father, the 4th Marquess of Hertford, took a house in Paris after the French Revolution and set about snapping up paintings by what were then dangerously unpopular artists, for a song. Frans Hals's Laughing Cavalier is probably the most famous painting here, or perhaps Jean-Honoré Fragonard's The Swing. The full list of painters in the collection reads like a who's-who of classical European art: from Rubens, Rembrandt, and Van Dyck to Canaletto, Titian, and Velázquez. English works include paintings by Gainsborough and Turner. There are also fine collections of furniture, porcelain, Renaissance gold, and majolica (15th- and 16th-century Italian tin-glazed pottery). The conditions of the bequest mean that no part of the collection can leave the building; this is the only place in the world you'll ever be able to see these works.