Symmetry and regularity abound in architectural models, often as a result of economical, manufacturing, functional, or aesthetic considerations. We show how recent work on symmetry detection and structure discovery can be utilized to analyze architectural designs and real-world artifacts digitized using 3D scanning technology. This allows reverse engineering of procedural models that facilitate effective exploration of the underlying design space and the synthesis of new models by modifying the parameters of the extracted structures and symmetries. We demonstrate the effectiveness of such an approach on a number of example designs.