 The first to open was the "Gemäldegalerie" on October 1, 1915.In the same year the "Natural Sciences Collection" was also able to move into the new building, but it was not until after the end of the First World War that the "Natural Sciences Museum" and the "Museum of Nassau Antiquities" reopened on 15 July 1920.Half of the picture gallery was to be used for changing exhibitions, which were carried out by the "Nassauischer Kunstverein" in the 1920s and early 1930s.