Opera 9 is one of the largest casemates in the Vallo Alpino with a length of about 80 m. The work is located in the center of the position of Rasun-Valdaora in Val Pusteria. It also served as a command post of the position. Its armament consisted originally of nine machine guns, one 47 mm gun and an observation turret. After the war four of the nine MGs and the AT gun were replaced by 9 cm guns.