Croatian State Archives

From the English Wikipedia page - there is more material on the Croatian Wikipedia page.

The Croatian State Archives (Croatian: Hrvatski državni arhiv) are the national archives of Croatia located in its capital, Zagreb. The history of the state archives can be traced back to the 17th century. There are also regional state archives located in Bjelovar, Dubrovnik, Gospić, Karlovac, Osijek, Pazin, Rijeka, Sisak, Slavonski Brod, Split, Varaždin and Zadar.

The website (in Croatian and English) is.