A coherent description of architectures provides insight, enables communication among different stakeholders and guides complicated (business and ICT) change processes. Unfortunately, so far no architecture description language exists that fully enables integrated enterprise modelling. In this paper we focus on the requirements and design of such a language. This language defines generic, organisation-independent concepts that can be specialised or composed to obtain more specific concepts to be used within a particular organisation. It is not our intention to re-invent the wheel for each architectural domain: wherever possible we conform to existing languages or standards such as UML. We complement them with missing concepts, focussing on concepts to model the relationships among architectural domains. The concepts should also make it possible to define links between models in other languages. The relationship between architecture descriptions at the business layer and at the application layer (business-IT alignment) plays a central role.