Bogbeagle
The NDB transmitter may be anywhere on the airfield (ditto for VORs). The ILS localiser is necessarily sited at the upwind end of the runway to provide accurate centreline guidance.
As you approach the runway on the centreline, the ILS localiser needle should be in the middle whilst the RMI needle will be pointing towards the NDB transmitter.
If you fly the NDB procedure, assuming the cloud ceiling is high enough, you will break cloud at or above MDH in a position where you can see the runway and visually position the aircraft on final approach. The procedure is designed to keep you clear of obstructions.