Free ART
There are more and more Free HQ-Pictures of famous ART in the web.And some are also in Public Domain.
Internet Archive
At the Internet Archive you can find some nice collections of HQ-ART-PicsAnd also some ART-Books for free.
Vincent van Gogh (1853-1890) - Paintings (200+ Artworks)
Paul Klee (1879-1940) - Paintings (200+ Artworks)
Edward Hopper (1882-1967) - Complete Prints (Book, SW, 1979)
Edward Hopper (1882-1967) - Paintings (3 Artworks)
wikiart.org
WikiArt is one of the Best Sources for Free Art in the Internet.Here you can find Hunderts of Artists and Thousands of Artworks.
Hieronymus Bosch (1450-1516) - Paintings (183 Artworks)
Lucas Cranach the Elder (1500-1553) - Paintings (232 Artworks)
Pieter Brueghel the Elder (1525- 1569) - Paintings (97 Artworks)
Pieter Brueghel the Younger (1564-16389 - Paintings (81 Artworks)
Jan Vermeer (1653-1675) - Paintings (41 Artworks)
Vincent van Gogh (1853-1890) - Paintings (1931 Artworks)