Historical American Building Survey - Great Resource
Thank you, atPollard for finding this fantastic resource which the images (I am told, but please satisfy yourself) are copyright free.
Check out these four pictures of the State Lunatic Asylum in Buffalo. With floorplans and photographs of the buildings themselves this is a great resource for maps in say, Call of Cthulhu scenarios.
I know I can just search google, but do you have a link to the Historical American Building Survey
I search from here:
MOST OF IT is public domain, but read this FYI:
"Material in these collections is generally considered to be in the public domain.
Access: Permitted, subject to P&P's policy on serving originals. This policy requires that copies of the drawings are served in lieu of the full-size originals. Field records are served by appointment only.
Reproduction (photocopying, hand-held camera copying, photoduplication and other forms of copying allowed by "fair use"): Permitted.
Publication and other forms of distribution: The original measured drawings and most of the photographs and data pages in HABS/HAER/HALS were created for the U.S. Government and are considered to be in the public domain. However, occasionally material from a historical society or other source is included in the photographs or data pages. These materials are noted by the presence of a line crediting the original source, and it may be necessary to receive permission from the owner of such material before it can be published. In all cases the courtesy of an acknowledgment is requested if material is used in a publication. Privacy and publicity rights may also apply.
Credit Line: Library of Congress, Prints & Photographs Division, HABS [or HAER or HALS], Reproduction number [e.g., "HABS ILL, 16-CHIG, 33-2 "]"