Renovation of business-critical software is becoming increasingly important. We identify fundamental notions and techniques to aid in system renovation and sketch some basic techniques: generic language technology to build analysis tools, a knowledge retrieval system to aid in program understanding, and a coordination architecture that is useful to restructure monolithic systems thus enabling their renovation. We argue that these techniques are not only essential for the renovation of old software but that they can also play an important role during the development and maintenance of new software systems.