Famous Paintings You Can't Get on Loan

The Guardian has a fascinating article about the few artistic masterpieces that are considered either too fragile or too precious to loan to other museums:

Girl with a Pearl Earring thus joins the select band of art treasures that never see the outside world. Botticelli's Birth of Venus never leaves the Uffizi in Florence; Las Meninas by Velázquez stays put at the Prado in Madrid; Picasso's Guernica remains just down the road at the Reina Sofia museum; and his Demoiselles d'Avignon can only be seen at MoMA in New York.

Other sedentary art works include La Joie de Vivre by Matisse, Le Facteur Roulin by Van Gogh and Les Joueurs de Cartes by Cézanne, which are unlikely ever to leave the Barnes Foundation in Philadelphia. It is impossible for the Isenheim altarpiece to leave the Unterlinden museum in Colmar, or for Degas' Petite Danseuse de Quatorze Ans to escape from the National Gallery of Art in Washington DC. Needless to say, the Mona Lisa is under lock and key in the Louvre, Paris.

So why are all these famous pieces so stay-at-home? Predictably the principal reason is their state of health. Many of them, including the Mona Lisa, were painted on wood and are very sensitive to climatic changes, making travel a major worry.