An integrated architectural approach is indispensable to control today’s complex organisations and information systems. It is widely recognised that a company needs to ‘do architecture’; the legacy spaghetti of the past has shown us that business and ICT development without an architectural vision leads to uncontrollable systems that can only be adapted with great difficulty. However, architectures are seldom defined on a single level. Within an enterprise, many different but related issues need to be addressed. Business processes should contribute to an organisation’s products and services, applications should support these processes, systems and networks should be designed to handle the applications, and all of these should be in line with the overall goals of the organisation. Many of these domains have their own architecture practice, and hence different aspects of the enterprise will be described in different architectures. These architectures cannot be viewed in isolation.