Kunstmuseum Linz is not a real museum but a project as part of the Nazi art policy. It is also known as the Linzer Führermuseum, Führermuseum, Gemäldegalerie Linz or—with reference to the underlying project—Sonderauftrag Linz. It was Hitler's intention to erect a new art museum in his "home town" of Linz. The project got underway in April 1938, a few weeks after the annexation of Austria, when Hitler visited the Oberösterreichisches Landesmuseum in Linz to discuss his plans for a museum with director Theodor Kerschner. In May, he spent a week in Italy, visiting numerous art museums, including the Uffizi in Florence. The plans for an art gallery in Linz must have taken shape during those weeks. In June 1938, an unofficial decree known as the "Führervorbehalt" (Führer reserve) ensured that he would have the final word on artworks and assets seized since March 1938 in Vienna, thereby making them available for his museum in Linz. The creation of the Linz art museum was therefore inextricably linked with the securing, seizure and expropriation of the assets belonging to persons persecuted on political and "racial" grounds. Initially, the Berlin art dealer Karl Haberstock, who advised Hitler on art, was to draw up distribution plans based on the "Führervorbehalt" for the artworks kept in the Zentraldepot für beschlagnahmte Sammlungen (Central Depot for Seized Collections) in the Vienna Hofburg. In June 1939, Hitler then appointed the art historian and museum director Hans Posse from Dresden as special representative for Linz. He was to put together "the best of all times" from the "seized possessions, Hitler’s existing collection and new acquisitions" for a new museum in Linz, as Posse wrote in his diary. From an art history point of view, the appointment of the experienced museologist Hans Posse put the Linz project on a professional basis. The new art museum was to have sections for Old Masters and for nineteenth-century art. There was no place for contemporary Nazi art, as shown at the Great German Art exhibitions. In 1940, Posse presented a first list. Of the 324 paintings in it, the majority, 174 in all, were from the Central Depot in Vienna. The basic inventory consisted of paintings from the collections of Alphonse Rothschild, Louis Rothschild, Oscar Bondy, Felix Haas, Rudolf Gutmann, Alfons Thorsch, David Goldmann and Felix Kornfeld. The inventory and distribution list drawn up in Vienna—apart from Kunstmuseum Linz, Viennese and provincial museums were also to obtain seized works—were subdivided by themes: in the case of paintings these were German, Old Dutch, Flemish, Dutch, English and Italian from the fifteenth to nineteenth centuries. With almost unlimited funds, including foreign exchange, Posse was able to add continuously to the Linz inventory through purchases on the art market and with objects expropriated during the war from occupied/conquered territories. After Posse's death in December 1942, he was succeeded for an interim period by his deputy Gottfried Reimer, before the art historian and museum director Hermann Voss took over in 1943. Unlike his predecessor, he no longer had the same amount of looted art at his disposal, although his acquisitions also included many works belonging originally to victims of the Nazis. Under Voss's directorship, it became increasingly unclear exactly which artworks were destined for the Linz picture gallery and which were to be used elsewhere, and it is therefore impossible to precisely define the Linz inventory. The albums in which Posse and later Voss compiled photographs of the new acquisitions provide a good insight into the planned design of the museum. The leather-bound volumes were presented to Hitler between 1940 and 1944 on special occasions such as Christmas or birthdays and may be regarded as a catalogue of the Führer museum. They contain around 1,300 objects. Apart from the picture gallery (including sculptures), the museum had other planned sections, including ones for graphic art and handicrafts (managed by Posse and Voss), and a weapon and coin collection. Fritz Dworschak, director of the Kunsthistorisches Museum in Vienna, was responsible from 1942 for putting together a coin collection, and weapons expert of the Kunsthistorisches Museum Leopold Ruprecht from 1943 with compiling a weapons collection for Linz. A separate library project was also planned for Linz under the responsibility by the Germanist and librarian Friedrich Wolffhardt. The Linz art museum was to be part of a planned new culture centre between the Volksgarten and the train station together with a library, opera house and theatre. Plans and models were presented by the architects Roderich Fick and Hermann Giesler but were never put into practice. The artworks intended for the museum were stored during the war in various depots, initially in the Führer's headquarters in Munich and then, from 1941, in the Reichskunstdepot (Reich art depot) in Kremsmünster, and finally in mine tunnels in Altaussee.

The Kunstmuseum Linz was thus never a museum and was never located in Linz. It refers rather to a collection of art objects of various origins, which were housed in different places and depots but are lumped together on account of their intended purpose. This has tended to confuse attitudes towards them at the time and later and to distort ideas about the reality of the project. The term "Kunstmuseum Linz" is still unclear today, and provenance researchers continue to identify the origins of the artworks intended for the Linz project, which in spite of some efforts after 1945 have not been returned to their owners and ended up in Austrian, German or other museums.