Schloss Hollenburg is a medieval castle near Köttmannsdorf. It is on a rock of the northern slope of the Drava valley. One Swiker, Lord of Hollenburg in the Duchy of Carinthia was first documented as a witness in the 1142 deed of the foundation of Viktring Abbey. He may have been a liensman of the ducal House of Sponheim; his son Reginher is mentioned as Lord of Steuerberg, he accompanied King Conrad III of Germany on the Second Crusade in 1147 and later appeared as a ministerialis of Margarve Ottokar IV of Styria.
The castle was of strategical importance due to its location at a Drava river crossing and the road to the Loibl Pass and the March of Carniola. Upon the extinction of the Hollenburg dynasty in 1246, it passed to the Styrian Lords of Pettau, in 1438 it was inherited by the House of Stubenberg. The structure had been severely damaged by the 1348 Friuli earthquake.
In 1514 the Habsburg emperor Maximilian I, stuck in the War of the League of Cambrai against Venice and highly indebted, sold Hollenburg to Lord Siegmund of Dietrichstein, elevating him to the rank of a Freiherr (Baron). The House of Dietrichstein had the castle rebuilt in a Renaissance style, finished in 1588. The Dietrichsteins held the castle until the extinction of the branch in 1861, it was acquired by the Wittgenstein family in 1913.
References:Redipuglia is the largest Italian Military Sacrarium. It rises up on the western front of the Monte Sei Busi, which, in the First World War was bitterly fought after because, although it was not very high, from its summit it allowed an ample range of access from the West to the first steps of the Karstic table area.
The monumental staircase on which the remains of one hundred thousand fallen soldiers are lined up and which has at its base the monolith of the Duke of Aosta, who was the commanding officer of the third Brigade, and gives an image of a military grouping in the field of a Great Unity with its Commanding Officer at the front. The mortal remains of 100,187 fallen soldiers lie here, 39,857 of them identified and 60,330 unknown.