Abstract: A building module, modular building constructions and methods for erecting same are disclosed. The module is of deep U-shape configuration, defining a space which is able to enclose various facilities within a building structure. A typical module includes a raceway and internal conduit system for power and/or communications systems etc. Preset-levelling and self-centering devices provide for quick erection of the modules in a wide variety of arrays and configurations to provide exterior walls and to enclose and define interior space.