Here, moviegoers watch a public viewing of a restored print of "Metropolis" in 2010 on Berlin's Pariser Platz square. Because of the explosive nature of the films, the archive feels obligated to copy them onto newer acetate film and then destroy many of the originals. Only the most valuable works are returned to the storage facility after a copy is made. This has generated considerable controversy among film historians and archivists. Important works have already been destroyed, including a 1911 film featuring Danish star Asta Nielsen. Preservationists would like the films to be saved until better methods are available for making digital copies.