Each Hardware or Person has to be assigned to a Site. This is the base location of them.
If you like to make a more detail model of your company, you can create Buildings, Sub Buildings (e.g. Floors) and Rooms. Hardware can be assigned to Rooms.
Rooms can also contain Racks and Patch Panels. This enties can be used in the module PNAC. e.g. Assign Switches to Racks.