Arnulf of Carinthia
Moosburg proper is the site of the "Arnulfsfeste", a hill castle first mentioned in an 879 deed. It was then located in the former Slavic principality of Carantania, which had become a Frankish march by the end of the 8th century. Arnulf of Carinthia, the Carolingian king of East Francia and Holy Roman Emperor, grew up here and used the castle as a "Kaiserpfalz" residence.