There are many points of contact between Gustav Mahler and Munich. In 1897 Mahler conducted the Kaim Orchestra (today's Munich Philharmonic), in 1901 he conducted the - unsuccessful - premiere of his 4th Symphony in Munich. A few years later Mahler seriously considered moving to Munich. On September 12, 1910 he achieved an outstanding success with the premiere of his 8th symphony, the 'Symphony of a Thousand'. Half a year after Mahler's death, Bruno Walter conducted the premiere of the 'Lied von der Erde' in Munich. Over the years, the BSB was able to acquire a small collection of Mahler autographs: the song 'Ich atmet' einen linden Duft' in the versions for voice and piano (Mus.ms. 6565, acquired 1959) and for voice and orchestra (Mus.ms. 20862, acquired 1990) as well as sketches for the 6th and 7th symphonies (Mus.ms. 7661, acquired 1966). The highlight of the earlier acquisitions is the magnificent autograph fair copy of the 8th Symphony. It was purchased in 1981 by Mahler's daughter Anna Mahler (Mus.ms. 13719). In 1998 the BSB succeeded in acquiring what is probably the most important collection of music manuscripts with works by Gustav Mahler, which was in private hands at the time. It originates from the collections of Hans and Rosaleen Moldenhauer. The 22 almost exclusively autograph manuscripts provide sources for seven symphonies and four songs by Gustav Mahler. The highlight are previously unknown autographs for the 4th and 10th symphonies as well as the songs on texts from the collection 'Des Knaben Wunderhorn'. These manuscripts are internal working manuscripts, whose musical text often still deviates considerably from the later form of the works, very often drafts and short scores. Here we find the most important parts of the orchestral writing on 2-5 staves. Since Mahler himself destroyed most of his sketches and drafts, these sources are among the rarest testimonies to his creative process.