The new Swiss Codes for engineering of existing structures. The Schweizerische Ingenieur- und Architektenverein (Swiss Society of Engineers and Architects) introduces the series of Codes SIA 269 as a tool that will provide guidance for their members to significantly improve engineering of existing structures. These standards will challenge the civil engineering community and allow for creativity. This paper presents the main content of the SIA 269 codes. Principles and activities are outlined. Main aspects of existing structures are discussed and illustrated by means of examples of existing steel structures of high cultural value which have been rehabilitated over the last few years already applying the state-of-the-art rules as establish now in the Codes SIA 269.