Bridges of high cultural value and aesthetic quality deserve respectful treatment and construction interventions must balance these assets with the severe requirements of utilisation. This is particularly relevant to structural engineers and bridge owners involved in rehabilitation or modification interventions. This paper presents, by means of eight bridges in Switzerland, examples of how interventions can be performed with adequate respect to cultural value. It is argued that the preservation of cultural value may go hand in hand with socio-economic, environmental and technical requirements following the principles of sustainable development. These requirements are met through the application of advanced structural engineering methods specific to existing structures. Extending service life not only adds value to bridges – it also leads to an appreciation of the art of structural engineering and the identity of the engineers themselves.