Many museums now offer CC0 access to the artwork in their collections. Here are a few:

• • Art Institute of Chicago
    More than 50,000 images of works in the collection, including the favorite, A Sunday on La Grande Jatte, by Georges Seurat.
  • Belvedere, Vienna
    Works by Klimt and Schiele are included in the collection with nearly 20,000 images
  • Birmingham Museums Trust
    Nearly 2,500 images from across the eight municipal collections looked after by the trust. More are gradually being added.
  • Cleveland Art Museum
    Open Access is a logical and exciting outgrowth of the CMA’s inclusive mission “to create transformative experiences through art, for the benefit of all the people, forever.” 30,000 works from the collection, including the expansive Asian collection.
  • Harvard Art Museums
    More than 200,000 images available from the university’s collections of 250,000 objects
  • J. Paul Getty Museum, Los Angeles
    The Getty makes available, without charge, all available digital images to which the Getty holds the rights or that are in the public domain to be used for any purpose. No permission is required.
  • Kunstmuseum Basel
    The Kunstmuseum Basel’s Collection Online website provides over 4,100 photographs of our works for download; all images are in the public domain.
  • Library of Congress, Washington, D.C.
    Millions of images from the national archives
  • Los Angeles County Museum of Art
    Nearly 20,000 images of artworks the museum believes to be in the public domain are available to download on this site. Other images may be protected by copyright and other intellectual property rights.
  • Mauritshuis, The Hague
    All the works of art of the Mauritshuis collection can now also be admired online. Most of the collection has been photographed in high resolution, allowing you to zoom in to the smallest details. More than 800 works, including Rembrandt, Vermeer, and many other Dutch and Flemish masters.
  • Metropolitan Museum of Art, New York
    Enjoy more than 375,000 hi-res images of public-domain works from the collection. Search the sites Open Access area.
  • Minneapolis Institute of Art
    Images of works of art identified as in the Public Domain (CC PDM) have been identified as being free of known restrictions under copyright law, including all related and neighboring rights. Mia’s collection contains over 50,000 works in the Public Domain! You can copy, modify, distribute and perform the works, even for commercial purposes, all without asking permission.
  • Munch Museet, Norway
    One of the world’s largest single-artist collections: 1,150 paintings and some 18,000 prints, free to download
  • Museum of New Zealand Te Papa Tongarewa, WellingtonAround 30,000 images from New Zealand’s state collections
  • Národní galerie Praha
    The Czech Republic’s national collections in Prague
  • National Gallery of Art, Washington, D.C.
    More than 51,000 works in the public domain
  • Nationalmuseet Danmark
    More than 50,000 images from 20 institutions across Denmark
  • Nationalmuseum, Stockholm
    6,000 images – most of the collection – via Wikimedia Commons
  • New York Public Library
    180,000 items, free to share and reuse
  • Paris Musées
    320,000 images from 14 Parisian institutions, including the Petit Palais and the Catacombs
  • The Rijks Museum
    Includes many famous works including many Vermeers and Van Goghs.
  • Smithsonian Institution, Washington, D.C. 
    As of 26 February 2020, 2.8m digitized images from across the Smithsonian’s multiple museums, research centers, libraries, and archives are freely available online.
  • Städtische Galerie im Lenbachhaus, Munich
    Full access to out-of-copyright works. Strong on Munich-based painters of the 19th and early 20th centuries
  • Statens Museum for Kunst, Copenhagen
    Around 15,000 works (of a quarter of a million) have been photographed in hi-res, with all public domain images free to download and use
  • Wellcome Collection, London
    Thousands of archival images from the science collections at the museum and library
  • Yale University
    Thousands of images of works in the Gallery’s collection believed to be in the public domain are available for free download through the Gallery’s website. Under Yale University’s Open Access Policy, anyone may use the Gallery’s open-access material without further application, authorization, or fees due to the Gallery or to Yale.