This volume documents the long-term initiative 'Safety Curtain' of Museum in progress, a project that is unique in the world. The exhibition series in the Vienna State Opera has represented a symbolic interface between performance and visual arts since 1998. It also creates a link between thorny historical questions and contemporary ways to address them. Beyond the actual curtain images that have originated over the years an associative and sensuous view to further related works of the participating artists in several different media forms is presented. The art project 'Safety Curtain', because of its exceptional quality, its year-long existence and its unusual dimension of 175 m² is singular and enables a distinctive perspective of art history of the past twenty years.