For the last 15 years, implementors of multiple view programming environments have sought a single code model that would form a suitable basis for all of the program analyses and tools that might be applied to the code. They have been unsuccessful. The consequences are a tendency to build monolithic, single-purpose tools, each of which implements its own specialized analyses and optimized representation. This restricts the availability of the analyses, and also limits the reusability of the representation by other tools. Unintegrated tools also produce inconsistent views, which reduce the value of multiple views. This paper describes an architecture that allows a single, minimal representation of program code to be extended as required to support new tools and program analyses, while still maintaining a simple and uniform interface to program properties. We present architectural patterns that address efficiency, correctness and the integration of multiple analyses and tools in a modular fashion.