If you want something that is handholdable, look into Hasselblad like a 500 C/M, super duper Zeiss lenses. For architecture, I recommend you look into a Fujifilm GX680III. It is a monster of a camera, really design for studio work and needs to be tripoded. But, it has built in tilts and swings for 'proper' architecture. If you are serious, then go for the Fuji ... If you're just testing the waters ... Buy something like JC recommended and get a little wet. Fuji makes a number of very good rangefinder MF cameras and Fuji lenses are exceptional.