Interested in the history of U.S. national security policy?
Check out the Digital National Security Archive, which “contains the most comprehensive set of declassified government documents available” and is comprised of “39 collections consisting of over 94,000 meticulously indexed documents, with more than 650,000 total pages.” If you have a particular interest, you can search the documents, bibliography, chronology, or glossary for relevant materials. If you are more inclined to browse, check out the Collections Guide, which provides links and summaries to the more specific collections, which range from The Cuban Missile Crisis: 50th Anniversary Update to The National Security Agency: Organization and Operations, 1945-2009.
Also be sure to check out the CIA Family Jewels Indexed, which contains 67 critical documents from the history of the CIA.
This resource is also available through LOLA.