Finding Images Online and In Print 

Google Images is probably the world's largest collection of freely available digital images.

To find the best quality images, do an ADVANCED Google Images search and request filesizes LARGE or EXTRA LARGE.

The best online collections of art and architecture images are:

ARTstor is a searchable collection of high quality images intended for teaching and research in the fields of art, architecture, and design.

CAMIO (formely AMICO) is a searchable collection of high quality images of artworks in museum collections.

American Memory -- historical collections for the national digital library.

Masters of Architecture -- high quality digital images of buildings and monuments.

Pidgeon Digital -- Illustrated lectures by architects.