Developing valuable context-aware applications is at the centre of research in Ubicomp. In this paper we want to describe our experience over the last years in designing and developing such applications and in integrating them to build homogeneous Ubicomp environments. We introduce the concept of modular integration of context-aware application by presenting the AwareOffice TecO?s test bed for all kinds of context-aware applications form the office domain. We will show how we can easily build new applications by simply exploiting the modularity of our system. Therefore we introduce some base applications of the AwareOffice in some detail and show how to build more complex applications by modularly integrating them.