Reusing original architectural elements made from iron, steel and aluminium seems to cause many structural and construction-physical problems in recreation of historical buildings from the 19th and 20th century. They often collide with modern technics, norms and pollutant management. Based on practical experience there will be given several examples of possible solutions at buildings from Josef Benedict Withalm (1848), Will Schwarz (1959) and Arne Jacobsen/Dissing + Weitling (1972).