Is it legal to reprint famous 'masters' artwork

Additional information
This is a more complicated question than you might think. (Aren't they all!) The Mona Lisa was painted long before the establishment of copyright laws. The Louvre in Paris owns the painting, and the Louvre generally allows its paintings to be reproduced as long as the reproductions carry the following attribution: "Musee du Louvre," the title of the work, and the name of the artist.
The thornier problem is that if you want to reproduce the Mona Lisa, or Starry Night, or some other famous painting, what you'd almost certainly be reproducing is not the painting itself, but someone else's reproduction of that painting in a book, or on a postcard or color slide. That first reproduction is almost certainly copyrighted by a person or an institution (a publisher, a museum, etc.). You'd need to get permission (that is, a license) to reprint the reproduction.