This is kind of the "hello world" example. Some outside - walls without any roof or windows.
To switch into "real" 3D-Mode select "rotate" from the camera controls list.
A basic bml-document is made up of two main blocks. Starting with "base_conf" which contains the building-information-model(BIM) definitions and the "building" block which contains the actual building. In theory more the one building could exist in any bml document but currently only one is supported.