Everyone in Austria who is interested in contemporary music knows Lothar Knessel and values him: as a radio voice on Ö1, as a docent at the Musicological Institute of the University of Vienna for the history of new music and especially musical theater in the twentieth century, and as a fellow initiator and founder of the Wien Modern Festival. What is less well known is his comprehensive collection of highly interesting documents that reflect his many and diverse areas of activity. This collection is now open to the public at the mdw (Vienna University for Music and Performing Art). It encompasses large areas of (chiefly) Austrian musical life since the middle of the previous century, which Knessl has helped to shape. A selection of the most diverse objects which illustrate this variety (photographs, texts, notes ...) is brought together in this volume.