The door is found in the Forest of Fallen Giants.

The key is found in the iron keep.

How to access Crown of the Old Iron King Dive into Dark Souls 2, browse your inventory and you'll discover you now possess a Heavy Iron Key. Opens the door in the Iron Keep leading to Brume Tower. Usage The iron door referenced in the item description is located in the hallway leading to The Last Giant in Forest of Fallen Giants . Past the altar deep within the Iron Keep and through a door is the tower that the Old Iron King used to produce iron. Heavy Iron Key. Remember one of the first bosses you fight the Last Giant? A piece of iron shaped like a key. For Dark Souls II on the PlayStation 3, a GameFAQs message board topic titled "Where do I use the Iron Key? As for the door it unlocks?

Heavy Iron Key is a Key Item in Dark Souls 2. Iron Key is a Key item in Dark Souls 2. The Heavy Iron Key is a key in Dark Souls II. ". The unearthy weight of this chunk of iron is a reminder of the Iron King's own immeasurable strength. This page details how to access the Dark Souls 2 Crown of the Old Iron King DLC, the second part of the Dark Souls 2 The Lost Crowns trilogy.