In this paper we address the problem of recovering 3D models from uncalibrated images of architectural scenes. We propose a simple, geometrically intuitive method which exploits strong rigidity constraints such as parallelism and orthogonality present in indoor and outdoor architectural scences. We show how these simple constraints can be used to calibrate the cameras and to recover the 3 x 4 projection matrices for each viewpoint. The projection matrices are used to recover partial 3D models of the scene and these can be used to visualise new viewpoints.