UNESCO Digital Library
The UNESCO Digital Library is a key tool for enabling UNESCO’s mission of building peace in the minds of people, in particular by “advancing the mutual knowledge and understanding, and encouraging cooperation among the nations in all branches of intellectual activity, including […] the exchange of publications, objects of artistic and scientific interest and other materials of information” (UNESCO Constitution).

In more concrete terms, it provides access to publications, documents and other materials either produced by UNESCO or pertaining to UNESCO’s fields of competence. These collections are accessible online or physically - at the library or the archives room. 
https://unesdoc.unesco.org/home
UNESCO
A government organization
France
Library general contact
library@unesco.org
https://en.wikipedia.org/wiki/UNESCO
No - we would need to spontaneously reach out to the current owners/custodians
https://unesdoc.unesco.org/search/72a71bb0-74c9-4ef5-a26b-934dd8b90ab8/N-5c07b41a-d529-4a92-b681-aafdc5a278fc
Yes
https://en.unesco.org/open-access/
open license multiple licenses
cc-by-3.0: Creative Commons Attribution 3.0 Unported