Search Tools to Discover Physical Archive Collections
The following tools can be used to search descriptions of archive collections. This will not provide images of specific items in the collection, but it can at least reveal what libraries and institutions own useful collections on a subject.
The Online Archive of California provides access to archival collection descriptions from several hundred cultural and historical institutions in California- covering many different topics of research.
"The Archives Portal Europe provides access to information on archival material from different European countries as well as information on archival institutions throughout the continent." A strategic partner of Europeana. (APEx project supported by the European Commission)