This 3D model was originally created with Sketchup 13 and then converted to all other 3D formats. Native format is .skp 3dsmax scene is 3ds Max 2016 version, rendered with Vray 3.00 Starting with a stairwell component, then duplicate, rotate and stacking them, then modifying walls, removing excess doors, then simply adding other simple pre-fabricated room and hallways components a complete building that can be very elaborate can be constructed in a very short time