Luke
I don't believe that Lufthansa have any combi 747's (where the aft end is for cargo and the front part for pax), so I can only think that you are refering to a normal pax 747.
All normal pax 747 aircraft have forward and aft cargo holds (and doors!) under the floor of the lower deck with the doors situated on the starboard side of the fuselage.
I'm fairly sure that KLM, for example, have combi 747's.
I suggest that you google for some photos and try to see the differences.