Self-adaptive systems and context-aware systems have been proposed to provide the ability for a software system to adapt itself at runtime to cope with changes in its environment and user needs. However, research in self-adaptation and context-awareness has been carried out largely in separate communities, with limited reference to each other. Research in self-adaptation is more concerned with how to adapt the system, while research in context-awareness is more concerned with how to model, process, and manage the context information. In general, context-aware adaptive software systems need to consider both perspectives in a holistic manner. With the objective to gain a better understanding of the relationship between context-awareness and self-adaptation to advance the research and practice in this area, we in this paper introduce a layered architecture that integrates both perspectives. In addition, we demonstrate our approach through the development of a context-aware adaptive vehicle route planning software system.