During the last 10 years, about 15 important monuments from the Middle Ages and the Renaissance period exposed outdoors have been restored in Germany. For cleaning, a mechanical removal of the dark layers of soot and gypsum or a permanent spraying with water is preferred to the use of pastes containing complexing agents. A treatment with benzotriazole is recommended. For the coating of the surface, acrylic resins and silicon resins have been used. -- AATA