Implementing an SOA at the enterprise level is a significant endeavor that is likely to take many years. During this time, we probably will encounter many obstacles and will have to cope with frequently changing requirements. It is therefore essential that we look at a realistic roadmap for rolling out our Service-Oriented Architecture. It is important that our architecture and our roadmap is designed to cope with the complexity and dynamics of an enterprise environment. Chapter 1 introduced an SOA-based enterprise IT renovation roadmap. In this chapter, we will focus on the architectural aspects of this roadmap. In Chapter 12 of this book, we will then focus on the political and organizational aspects.