From the Wikipedia page [1]

The Bulgarian Historical Archive (Bulgarian: Български исторически архив) functions as part of the SS. Cyril and Methodius National Library and keeps more than 1.5 million documents and a separate collection "Portraits and Photos" consisting of 80,000 photos all of historical importance for Bulgaria and the Balkans. It was established in 1878

The website, in Bulgarian, is [2]

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.