There are ten large Iron Doors found throughout Mount Grimrock's dungeons. They all contain valuable treasure, but require a special touch to open - either finding obscure keys, or solving riddles, or pressing hidden switches. On this page, you'll find details on how to open all of them.
Level 1 Iron Door

The first Iron Door can be found near the stairs leading down to Level 2 - Old Tunnels. Opening it is actually fairly simple - there's two hidden switches on the walls of the room, one of them at the northwest end, the other at the southeast. Press both of them and the Iron Door will open up.

Reward: Whitewood Wand
Level 2 Iron Door

The second Iron Door is found near the end of Level 2, in the crypt area where you first fight an Undead Legion. You'll spot a demon statue on the wall and a floor switch, as well as the Iron Door. To open it, face the demon statue and stand on the floor switch. You'll need to stand still for about 15 seconds before the Iron Door creaks open. Get ready to back off quickly, as an Undead Legion hides inside to surprise-attack you.

Reward: Fire Bomb x3
Level 3 Iron Door

When you reach the second room at the middle of level 3 (it has a central pillar, and is just east of the "portal room", through some spider-infested tunnels), you'll note it has several sconces along the walls. Place two Torches on the east and west sides respectively (none on the central pillar) and a secret door will open in the northwest corner. Step through and flip the lever, and the Iron Door seen through the grating will open. Backtrack to the portal room, and reach its north side. To get past the pit blocking your way to the Iron Door, you might need to remove an object you have holding down the nearby floor switch.

Reward: Huntsman's Cloak
Level 4 Iron Door

To open this difficult Iron Door (located near the exit to Level 5), you'll need to do some lateral thinking. When you've passed the Trails of Thought test on Level 4, and are in the hallway leading towards the central room, look for an alcove. Press the hidden switch on the wall there, and run forward as quickly as you can. Inside the central room, two platforms have raised up, leading you to another wall switch. Press it, and then run back to solid ground. With the switch pressed, the portal in the middle of the room will disappear. Drop down the newly-revealed pit and you'll find yourself inside a cell within Level 4's basement. Once you've made it back to Level 4 via the portal, use the Gear Key on the lock near the Iron Door for your well-earned reward.

Reward: Chitin Greaves
Level 5 Iron Door

The Level 5 Iron Door is right near the stairs to Level 6. To open it, you'll need to solve an interesting riddle: rest in the gaze of the dragons, as a nearby scroll mentions. How to do this? You may have noticed two dragon statues throughout the level (marked A and B on the map to the left), each looking in a direction. Trace the gaze of each to the point they intersect (X), and stand in it for a few moments until you hear the Iron Door open in the distance.

Reward: Lurker Vest
Level 6 Iron Door

Level 6 is built around collecting four Round Keys to progress. However, only three are actually required to continue onward - the fourth is used to open the Iron Door near the stairs to Level 7, if you took the time to explore all of Level 6. Please see our walkthrough for more details on all the Round Key locations.

Reward: Chitin Mail
Level 7 Iron Door

Past the stairs down to Level 8, you'll come across a chamber with the Iron Door, a pit in the middle, three demon statues and three receptacles. As soon as you enter, the demon statues begin firing spectral orbs. Your goal is to prevent all of them from reaching the receptacles. You'll have to move left and right quite quickly to stop all of them, but your reward is well worth the effort. Note that if you fail, you'll be teleported outside the room, but you'll be able to try again as much as you want.

Reward: Chitin Boots, Scroll of Enchant Fire Arrow
Level 8 Iron Door

The Level 8 Iron Door can be found near the stairs down to Level 9, and must be opened with a Gear Key. The Gear Key itself can be swiped from the very end of the Lightning Conduit area - look for a switch on the north wall right near the end to open up a hidden chamber. For more details, please see our Level 8 walkthrough.

Reward: Helmet of Valor, Frost Quarrel x4
Level 9 Iron Door

The Level 9 Iron Door is one of the easiest to open in the game... provided you have the right item. You'll need a Bone Amulet to solve the riddle and open the door - just place it on the shelf nearby. A Bone Amulet can be found all the way back on Level 2, so you might have some backtracking to do!

Reward: Zhandul's Orb
Level 10 Iron Door

The level's Iron Door is the last of its kind in the game, and is found near the level's Crystal of Life. Opening it is actually quite straightforward. Early in the level, you'll have come by a Red Gem when solving a puzzle. Take the Red Gem and place it on the shelf next to the Iron Door to open it up.

Reward: Crookhorn Longbow, Throwing Axe