The Germanic National History Museum is by far the best and most impressive museum I've ever been to. If you're ever in Nuremberg you should set aside an entire day just for this museum. We've been there 7 hours and haven't even seen everything and it's stuffed with countless impressive original relics. Everything is there; architecture, clothes, tools, documents, arms and armor, coins, art pieces, musical instruments and more.
And it's located in an old cloister so even parts of the halls you're walking through are historical.