One of the most impressive castles of the region towers high above Frangarto between Appiano and Bolzano: Firmiano Castle was mentioned for the first time in 945 AD as "Formicaria" (anthill). A century later, the property was handed over to the prince-bishop of Trento by Conrad the Salic. In the 12th century, it was already known as Firmian. Its German name, however, Sigmundskron, dates back to the 15th century when Sigismund, Archduke of Austria, back then Count of Tyrol, purchased the building and had it converted into a fortress. In the following centuries, the castle fell into decay until the end of the 20th century when the Province of Bolzano took it over.

But already in the decades before, Firmiano Castle gained great significance for South Tyrol's history: It was in 1957 when it was venue for protest rallies guided by Silvius Magnago against the Paris Agreement. The statement "Away from Trento" went down into history and is carved in stone on the castle's area today. After extensive works on the building, in 2006 the MMM Firmian, the 4th mountain museum by Reinhold Messner, was inaugurated. The complex with its donjon, the residential tower, the curtain wall and the higher and lower castles houses also a tavern and offers a magnificent view on Bolzano: It can be reached in half an hour by foot from Frangarto (Frangart).