The Iron Keep is a vast fortress surrounded, and slowly sinking into, an immense mass of molten iron.
In the center lies a large foundry filled with falling platforms, along with one that can be submerged into the iron to kill enemies.
The Iron Keep was once home to the mighty Alonne kingdom, ruled by a king obsessed with making an unbreakable empire. He had a son, the prince, who had a wife, the princess, and another secret true love. The princess grew jealous and eventually turned herself into Mytha, the Baneful Queen in pursuit of ultimate beauty. She was banished to the Harvest Valley and the kingdom slowly began to succumb to fire "that rose from the earth".
- Threshold Bridge: After arriving in the Iron Keep, from the Earthen Peak elevator, the bonfire will be at the bottom of the set of stairs to the left of the main bridge.
- Ironhearth Hall: After defeating the Smelter Demon, this bonfire is located in a small room, at the top of a set of stairs, opposite the entrance to the boss room.
- Eygil's Idol: Advance through the Iron Keep towards the Old Iron King. Upon reaching a room with a flame mechanism in the middle and spikes on the wall, scale a ladder on the opposite side of the room that you entered to locate this bonfire.
- Magerold of Lanafir (merchant)
- Lucatiel of Mirrah (White Phantom - summonable for the Smelter Demon boss battle; her sign is located next to the drawbridge near the fog gate.)
- The Pursuer (spawns in the room where the Smelter Demon was after defeating it)
- Oliver the Collector (SotFS)
- Armorer Dennis (SotFS)
- Fencer Sharron (SotFS)
- Dull Ember (corpse, not present in SotFS)
- Lightning Winged Spear (guaranteed drop from Mimic)
- Pharros' Lockstone (chest)
- Black Knight Greataxe (corpse)
- Black Knight Greatsword (chest)
- Grand Spirit Tree Shield (chest)
- Protective Chime (chest)
- Ring of Blades+1 (guaranteed drop from The Pursuer)
- Sublime Bone Dust (chest)
- Red Leech Troches and Large Soul of a Nameless Soldier (corpse on a pillar next to the incinerator)
- Iron Key (corpse)
- Porcine Shield (chest, following the Smelter Demon)
- Chaos Storm (chest in lava area of room with Belfry Sol Entrance)
- Fire Seed (corpse close to the chest containing Chaos Storm)
- Phoenix Parma (chest in the pool of iron next to Smelter Demon boss fight)
- Bonfire Ascetic (found across fire rocks near the bridge in first area)
- Dark Armor (guaranteed drop from Mimic, not present in SotFS)
- Covetous Gold Serpent Ring (corpse inside an iron filled pot)
- The bridge where the first bonfire is found is a popular PvP area where many people leave their invasion signs.
- Concerning players who want to reach the items on the lava, it is important to note that there are jars filled with water around the keep. Rolling through them will boost the player's Fire defense by an amount equal to Flash Sweat, and most importantly will stack with it. Adding in armor and rings with good fire resistance as well as other spells will boost the players' fire defense enough to withstand the damage of the lava.
- Lore - dialogue with Laddersmith Gilligan.