Raldbthar

Description
This ruin is a more complex dungeon than most. The first level is infested by bandits, led by Alain Dufont, whose death is an objective of the Dark Brotherhood quest, Mourning Never Comes. The Raldbthar Deep Market is occupied by Falmer. Players will also encounter Dwarven Automatons. At the end of the dungeon, the player may exit to Skyrim or Blackreach.

Walkthrough
Upon entering the ruins, You will see a large room with a flame trap blocking the doorway. Use Whirlwind sprint to go through it without getting burned, and you will see Alain Dufont, otherwise do the following. Down the hall and to the left is a bandit sleeping on a bedroll. Even further will be a charred skeever impaled by a pole that is set up infront of the dwemer flame trap so it willl cook. Take a left down this hall and fight through three more bandits.

Head down the corridor to a large room with many Falmer and two Skeevers in a pen. Head up the stairs on the far side, and then down again to a button that drops a draw bridge. Proceed up and across until there is a room with 4 buttons and a blocked hall to the left. The button on the left will activate a fire trap, the second from right will open the gate. Next is a room with a few levelled Falmer and two Chaurus behind a locked gate to the left. There is a bridge with a button labelled "unpowered". Go to the stuck gears in the room and remove various bones jamming the cogs to power the bridge. Note that one set of stuck gears is located beneath the bridge underwater. After unjaming all the gears, press the button on the bridge, which will activate a Dwarven Centurion. After defeating it go thorugh the door that was behind it

At the end of Raldbthar there is a Dwarven Mechanism that connects Raldbthar to Blackreach.

There is another section with a chest above the pathway before the room with the final boss. Climb the pipes and use the Whirlwind Sprint to get across to the ledge.

Tips

 * If trying to use the Dragon shout "Whirlwind Sprint" to cross the bridge, it is wise to save your game first.
 * The Centurion then rises on the other end of the bridge. Keeping at safe distance and using a ranged attack (bow or spells) is advised; the Centurion's steam attack can be devestating. One strategy is to run into a Falmer nest, defeating its attack range. It is also possible to press the button once more when he is on the tip of the bridge to send him to the ceiling; At that point, get his attention, and he will fall into the water and die.
 * Another tactic to kill the centurion, is the get behind the door he comes out of. Open it quickly and use a conjuration spell to distract him. While he is distracted kill him without harm. Having the Conjure Dremora Lord spell or Sanguine Rose makes it possible to kill the centurion in seconds without ever having to go anywhere near it. Simply cast its spell into the centurion's chamber as soon as the bridge drops. The Dremora will finish the Centurion off before he even takes a step, allowing entry to the door behind it.

Noteable Items

 * Skill Book (Sneak): 2920, vol 08 - Last Seed
 * Unique Weapon: Aegisbane
 * Human Flesh - A rare Alchemy ingredient - Located in the market in the first room with falmer by the skeever cage

Bugs

 * The various bones jamming the gears powering the bridge may spawn on the floor or near the gears, instead of wedged in them.
 * The objects jamming the gears may not respond to the player. Backtracking to the area that the bandits were in and then returning may fix this. (Xbox360)
 * If the player returns to the dungeon upon completion, the jammed gears may reset but the objects jamming them might not. This makes it impossible to access the end of this dungeon after reset.
 * On PC, you can type tcl in the console to disable clipping and fly through the bridge. Until a bugfix is released this can at least be used as a workaround.
 * A possible method for avoiding the afforementioned bug is to exit the dungeon from the front. Then complete Dark Brotherhood Contract For Muiri by returning to her. Upon completion, you may now go north of Winterhold in search of Septimus Signus's Outpost. In this order, I returned to the dungeon as I left it with no bugs.
 * The boss, who would normally attack, may follow you without attacking.
 * When trying to leave Blackreach through the Raldbthar Dwarven elevator to Skyrim, the game may freeze. (Xbox360)Raldbthar.jpg (not fixed by patch)
 * Sometimes upon entering the ruins after doing the Dark Brotherhood mission you will not be able to proceed deeper into the dungeon due to an invisible wall.
 * When entering the water to un-jam the cogs the game might crash, save first. (ps3)
 * Sometimes, when unable to remove the items to power the button, exiting the area to the previous one and then returning does not fix the problem. It can glitch even more and cause the pieces to be immovable objects on the floor. (PS3)