During the Nazi era, Salzbergwerk (salt mine) Altaussee in Upper Danube Gau was one of the most important depots, along with Schloss Thürnthal, managed by the Institute for Monument Preservation in Vienna. In the first half of 1943 the Steinberg tunnel, an already disused part of the salt mine, was considered by Franz Juraschek, Gau curator in the Upper Danube, and Herbert Seiberl, head of the Institute for Monument Preservation, as a possible salvage depot – on account of the atmosphere in the mine determined in several expert opinions, including one by the chemist Maximilian Eder (60–75% humidity, 6–8°C temperature), the accessibility and the remote location. After an agreement had been reached in early August 1943 between the Institute for Monument Preservation and Alpenländische Salinen regarding the temporary storage of artworks, the first transport left Vienna on 25 August 1943 and arrived at the mine the following day. It contained cultural objects from Wiener Neustadt, e. g. objects from the municipal museum and the Lorenz Luchsperger's statues of the apostles from the cathedral. The Monument Preservation employees Eva Kraft, Linde Schrader, Alice Hoyos and the restorer Emmerich Bergthold were responsible for the photo documentation and inventory of the stored works, while Seiberl was responsible for the salvaging. Transports left Vienna thereafter every month. In October 1943 secured artworks belonging to Jewish collections administered by the monument authority arrived for the first time. Salvaged items were evacuated to Altaussee from the Gau Upper Danube, for example from the library of the Historical Research Institute of Reichsgau Upper Danube (manuscripts and codices from the abbeys Kremsmünster, St Florian, Wilhering and Hohenfurt closed by the Nazis), as well as the Altdorfer panels from St Florian Abbey, the Mount of Olives group from the Dominican church in Steyr and numerous artworks from Lambach. From February 1944 privately owned items were transported there from Vienna and Linz. From January to September 1944 artworks for the planned Kunstmuseum Linz were also moved from Kremsmünster to the salt mine, supervised specially by a local restorer Karl Sieber. In the first half of that year, cultural items from the expropriated collection of the banker Jean Baron Cassel van Door, which had arrived from Paris, undistributed items from the seized Viennese collections of Alphonse and Louis Rothschild and salvaged items from looting by the Reichsleiter Rosenberg Taskforce in western Europe were moved from Neuschwanstein and Herrenchiemsee castles in Bavaria. Added to this were stained glass windows from Maria am Gestade church in Vienna, the Franzensburg in the Laxenburg complex, and the photo and map collection and parts of the library of the Institute for Monument Preservation. In May 1944 transports also commenced from the "Führerbau" in Munich, which continued until April 1945. In addition, in September 1944 seventy pictures from the Schack-Galerie in Munich and the Ghent Altarpiece, previously stored in Neuschwanstein, were moved to the mine. The last major transport to arrive was the collection belonging to the German-Dutch banker Fritz Mannheimer. With the impending defeat of Nazi Germany, August Eigruber, Upper Danube Gauleiter, had four crates with bombs brought to the mine on 10 and 15 April 1945 with a view to destroying the artworks stored there. On Seiberl's initiative, many items were moved, in some cases within the mine, and in others cases to Bad Aussee and Lauffen. On 3 and 4 May, mineworkers removed the crates from the mine, referring to an order by Ernst Kaltenbrunner, head of the Reich Security Head Office. The following day, several entrances to the mine were blown up and not cleared until mid-May 1945. On 8 May 1945, the 3rd US Armored Division arrived in Altaussee, and the mine was handed over to the US Army. From then on, most of the artworks were transferred in numerous transports to the Central Collecting Point in Munich. Items whose Austrian provenance had been ascertained were left initially in the mine, mostly items belonging to the state or church, along with objects whose provenance needed to be verified by the Austrians. A few items, including the Rothschild family coin collection, remained in the mine until 1963. At the end of March 1946 the United States Forces in Austria handed over the art depot to the Republic of Austria, and its administration was taken over by the Bundesministerium für Vermögenssicherung und Wirtschaftplanung (Federal Ministry for Securing Property and Economic Planning). From 1966 until well into the 1970s, the Steinberg tunnel of Altaussee saltmine was enlarged in accordance with the Hague Convention as a central salvage site for Vienna's major collections and was placed under special protection until September 2000.