The Thuns are one of the oldest and most powerful noble families of the Trentino.
The name "de Tono" or "de Thono", later altered to the German form "Thun" or "Thunn", derives from Ton, their place of origin, in the Non Valley.
The Thuns built their first castles in the Trentino area: Visione, S. Pietro, Castelletto, Belvesino, and the actual Thun Castle. The family’s power eventually spread to the Non and Sole Valleys, where they owned the castles of Bragher, Castelfondo, Altaguardia and Caldès.
Being part of the Tyrolese nobility in 1472, the family would become counts of the Holy Roman Empire in 1629.
Towards the end of the 14th century, the Thun family was already divided in various branches, and in the 17th century the important Bohemian line, with numerous properties in Bohemia, Silesia and Thuringia, became part of the family.
The Thun Castle descendants, beginning with Luca (1485-1559), remained owners of the castle property until 1926 when it was then passed on to the Bohemian branch of the family.