J. Paul Getty MuseumAccess to the art collections at the J. Paul Getty Museum in Los Angeles.
Heilbrunn Timeline of Art HistoryA chronological, geographical, and thematic global-exploration of art from pre-history to the present, as represented in the Metropolitan Museum of Art's collection.
Louvre MuseumAn interactive museum experience on the web! This site allows visitors to tour the palace's galleries and gardens, as well as view 35,000 works and 140,000 drawings from the permanent collection.
Metropolitan Museum of ArtView Exhibitions, Study and Research museum collections and art movements, visit collection databases, or even plan your own trip to the MET.
Museum of Modern ArtExraordinary exhibitions and collections of modern, contemporary, established, and experimental art forms.
National Gallery of ArtView images and detailed descriptive information of hundreds of pieces in the National Gallery of Art's collection.
Art ResourceAn image resource which has claim to being "the world’s largest photo archive of fine art, offering a range of material from prehistoric times to the present."
VADSOver 100,000 Art images, from various collections, available for Academic learning, teaching, and research.
Wikimedia CommonsImages that you can freely use papers, projects, presentations, websites, etc, etc... the possibilities are endless! They are in the public domain, so you do not have to worry about violating copyright.