Staircase at the Courtauld. Source: Mike Peel via Wikipedia.
Courtauld Institute of Art
Paul Mellon Centre for Studies in British Art
The Centre's offers major collections of images of British art. Many images are online. Others, originally collected by the Tate Gallery, exist offline at the Centre's Bedford Square address. These offline images can be searched via the Centre's library catalogue.
Warburg Institute
A unique collection of photographs documenting the icongraphical tradition in Western art. Only accessible with a letter of recommendation from an academic: see our information about the Warburg library for more information. As of January 2023, 20% of the collection is available as online images. The Menil Archive of the Image of the Black in Western Art is not online, though an index is available.
Most archives will also contain rare, often unique, images.