In this talk we introduce a logical viewpoint on architectures. The logical viewpoint is based on the distinction between symbolic and semantic models of architectures. The core of a symbolic model consists of its signature that specifies symbolically its structural elements and their relationships. A semantic model is defined as a formal interpretation of the symbolic model. This leads to more precise characterization of the concepts introduced in IEEE standard 1471-2000, and provides a formal approach to the design of enterprise of architectural description languages and a general mathematical foundation for the use of formal methods in enterprise architectures. Joint work with F.S. de Boer, J. Jacob, A. Stam and L. van der Torre.