Skyrim:Nchuand-Zel

Understone Keep, the castle in the city of Markarth, comprises the exterior portions of Nchuand-Zel, which is actually a cavernous Dwarven castle carved deep into the mountain, being excavated under the direction of Calcelmo.

 
Related Quests
 
 

Nchuand-Zel Excavation Site
The excavation area consists of a corridor running through two connected, square rooms, each with stone staircases on all sides. All staircases are blocked by crumbled stone except the one on the far left, which provides access to an area clearly being excavated. In the first chamber, in addition to the dwemer metal items and scrap lying around, there is an unlocked chest among the rubble at the top of the blocked stairway at the far end of the room. 

An excavated path to the left leads to the next room, where there are two stone pillars in the relatively large cavern, along with excavation scaffolding that you descend. A potion is found on the ground near a cart at the entrance to the cavern. In the cavern itself, the shorter of the two pillars has a respawning Dwarven dagger, a blacksmith's draught, and a piece of bent Dwemer scrap metal on it. You can jump down onto the pillar from the ledge near the cart. There is a small unlocked chest at the top of this room to the right of the crumbled door, which can be reached by jumping up the boulders above the wooden platform on the right. At the bottom of the room are some bones and several food barrels. At the top of a wooden ramp, an iron ore vein is found near three of the barrels, while a second vein is found on the western wall.

The passage to the south holds three frostbite spiders, as well as two further iron ore veins: one on the ground by the turning to the east, and the other on the south wall a short distance farther along the same section. A corundum ore vein is found a little farther on beside an egg sac that can be harvested for a spider egg. The passage then opens into another larger chamber, where a giant frostbite spider named Nimhe will descend through a large hole in the ceiling immediately adjacent to the entrance to Nchuand-Zel. Nimhe is the target of the quest Nimhe, the Poisoned One.  There is a second egg sac that can be harvested in this chamber, as well as the corpse of Alethius, who carries his notes, which when read initiates The Lost Expedition quest. This quest provides the opportunity to reactivate Nchuand-Zel's automated defenses. The expedition consisted of a group of Markarth mages along with a guard of Imperial Soldiers that has ventured into Nchuand-Zel against Calcelmo's advice.

Nchuand-Zel
thumb|right|Nchuand-Zel, a city under a city.
Nchuand-Zel consists of a giant interior space with a central tiered walkway that provides direct access to Nchuand-Zel Quarters and Nchuand-Zel Armory, and indirect access to Nchuand-Zel Control (actually, you can directly access Nchuand-Zel Control by standing on the raised cement slab near the cavern entrance and jumping to the rocky ledge just nearby, strafing a bit to get up the last section). The floor of the central room is flooded, and much of the bottom walkway has crumbled, making navigating the room a bit difficult. Falmer have occupied the entire ruins, and can be found in the central room and in each of the three interior zones (see below). There are many Dwemer items found throughout every area of the ruins, which may cause you to make many return trips to offload batches of collected loot. This also makes the ruin an ideal target for finding the ten Dwemer cogs needed for Arniel's Endeavor.

On entering, a ramp descends. At the bottom, there is a pressure plate that triggers a slicer trap from the right wall. Turning left, the path leads out onto a wide walkway over a huge open area, with spiraling ramps leading down to different levels. Directly ahead and halfway to the first portico is a leveled Falmer. You will see several doorways at different levels to your right, but ignore them for now. The first portico has a ledge to the left with a Falmer on it. With sufficiently high sneak skill, this Falmer may fall off the edge if you take out the first with a bow. The ledge can then be used to take out the remaining Falmer. Past the first portico, the path continues to a second portico that has three levels; you are on the top level. To the left, another Falmer is standing in front of an inactive Dwarven scuttle, and may be difficult to see. There is a door to the left of that Falmer which leads into Nchuand-Zel Quarters. Ignore this for now, and finish clearing this room. A ramp spirals downward from the back of the top portico to the second level, where another Falmer is standing. There is another ramp descending to the lowest level, and a walkway heading east. Descending to the lowest level brings you to an adept-locked gate to the right with an unlocked chest behind it. Back on the second level, following the walkway to the east brings you to another portico, where yet another Falmer waits, with some human bones and a random battleaxe on the ground. If you continue past this portico, the ramp starting to the east continues down and enters the water. Just next to it (as you are now facing, it will be to your right), under the water, is a door, and behind this are two random potions.   

As previously mentioned, there is a doorway to the Quarters on the south side of the top level. To the west side of the large area are four doorways. The southernmost door has no ramp, and is accessed through the Quarters section. Moving south to north, there is a doorway on the lowest level to the Armory. The next door, on the second level, is the exit from the Armory, which in turn allows access to the farthest northern door, which leads to the Control section. Egress back to the original entrance ramp is via a ledge just north of that door.

The normal route is to clear out the main room, then the Quarters, then pass through the Armory, and finally exit back to the main room to access the Control section. However, it is possible, although not necessarily advisable, to jump onto the exit ledge from the Control section from the start and clear the area in a different direction; this may also be used as a faster way to enter and exit the ruins when completing multiple loot trips.

Nchuand-Zel Quarters
On entering the zone from the southern door in the main area, there is a small alcove to the left containing several Dwemer items. The passage continues ahead and then turns right. Ahead you can see a Falmer, but be careful, as down the steps, just out of sight, a second Falmer awaits. Once these have been dealt with, you are now free to either descend the stairs or continue straight ahead. It does not matter which direction you take first.

Steps Downward
You will end up in an area that has two dead Falmer, a set of stairs leading up, and a live Falmer on the stairs. There is an elemental rune trap at the top, and two Falmer, one with a frostbite spider for a companion, just beyond. It's possible to kill one of the Falmer on the steps and have the others race into the trap, often killing one and damaging another, and possibly the spider as well. At the top, on the right is a tree. The Falmer with the spider will be in this area, if not previously alerted to your presence. If the trap is not sprung by the Falmer, hang as far right as possible to pass it. There is a table ahead with several Dwemer items, a small coin purse, three loose gold coins, and a bottle of wine on top, and the body of Stromm, one of the expedition mages, and two food sacks beside it. He carries his diary. To the right is another dead Falmer and two unowned bed rolls. There is a second elemental rune trap by the tree. 

From the top of the previous stairs, you can go left or straight ahead. To the left, following the passage as it takes a couple turns leads to an area containing a single Falmer standing by a doorway to the right into a bedroom, which contains a stone unowned double bed, a Dwarven shield at the head of the bed, one of two dressers by the foot of the bed, and a stone table to the left. There is a frostbite spider farther along the passage standing by another doorway into a second bedroom, which contains four unowned single stone beds, a stone table, and an unlocked chest. Opposite the first bedroom is a dining area, with a long stone table with two metal benches on either side and two sets of shelves at the far end. Several Dwemer items, including forks and spoons, have fallen to the floor. Return to the junction at the top of the stairs. Straight ahead from the top of the stairs, there are several stone tables on either side, two metal units to the left, and stone chairs all around. Through an opening ahead, there is a partially caved-in section on the right, and the bodies of two Falmer and one of the Imperial soldiers on the left. The room at the end is a torture chamber, and contains a torture rack with a wooden table beside it that has two random poisons on top, several small cages, and stone tables around the room with many human bones and blood all around. To the left as you enter is a lever that activates three spears that repeatedly stab down over the table beside it. Once this area has been fully explored, return to the top of the first flight of stairs in the zone and continue straight ahead. 

Straight Ahead
Continuing down the hall, the wall ahead has partially collapsed, and you can look through a gap to see farther ahead. It is possible to snipe through the gap at a Falmer or two and a frostbite spider; however, this can alert a large number of Falmer to your presence, who then all converge on you, leading to a fierce battle. To the left is a Falmer at the top of some stairs leading down. To the right is an adept-locked gate with an unlocked chest, a random potion, a set of shelves holding a random poison, a random helmet, and an apothecary's satchel, and several Dwemer items scattered about. Continuing down the stairs, you will see four Falmer clustered together. High sneak and bows work wonders here, as do Frenzy spells. Past the Falmer, the passage turns right, and a stairway leads back up. At the top and to the left is the Falmer with a frostbite spider you could see from the other side of the partially collapsed wall. To the right is another Falmer. At the top of the stairs, the passage turns right and climbs another flight of stairs before turning left and descending a ramp. At the bottom of the ramp is a door back out to a ledge in the main area of Nchuand-Zel, which holds an unlocked chest. To the left is another room containing a final Falmer, and left again is another unlocked chest. Now backtrack and take the exit out onto the ledge in the main area, collect the items from the chest, and drop into the water below to land near the entrance to Nchuand-Zel Armory.

Nchuand-Zel Armory
Upon entering the zone, you will see a stairway straight ahead, and a passage to the left passing under a ledge accessed from the top of the stairs. There is a Falmer on the ledge, and another at the top of the stairs to the right, just out of sight. The passageway on the lower level leads to an adept-locked gate that can be avoided. At the top of the stairs, there is a flight of stairs to the right, with a Falmer and a chaurus patrolling the passage at the top from left to right. To the left is a flight of stairs leading back down, but take care, as there is a pressure plate at the top that triggers a flame spout trap in front across the width of the passage. At the bottom, the passage turns left again, with another pressure plate in the middle that triggers a spear trap from both sides. The passage then enters a chamber. At the bottom of a stairway below you is the locked gate that was avoided earlier.

To your right in this chamber, you will see several inactive Dwarven automatons on pedestals. There are two wall-mounted Dwarven scuttles, one on either side of the room, from which leveled Dwarven automatons can spawn. They do not spawn if you sneak past the openings. The first gate is unlocked, and contains various metal items and an unlocked chest. The second gate has a leveled lock, and contains a full set of Dwarven armor. The third gate has an expert lock, and contains an unlocked chest. The final gate is open, and contains three sets of shelves holding a few plates. At the foot of the centurion is an unlocked chest, and in front of this is the body of Erj, another of the mages from the expedition, who also carries his notes. Nearby is a dead Falmer. The automatons are bugged (see here for details). Return back to the junction, taking care to avoid both pressure plates, and keep going up the stairs. Through the door at the end of the passage is a ledge and walkway in the main area.

Ramp to Control in Nchuand-Zel
On this ramp, you will find the bodies of two more of the soldiers sent to guard the expedition, as well as the body of Krag, another of the mages, who carries his journal. There is a copy of the Alteration skill book Sithis on a bench. This area features a flute, a food sack, a baked potato, a goat cheese wedge, and four bed rolls, as well as a centurion opposite the door, which will remain inactive until you have reactivated the defenses in Nchuand-Zel Control. At the top of the ramp is the door to Nchuand-Zel Control, and to the right of this door is a ledge back to the initial walkway. Along this ledge is a moonstone ore vein. (Tip: To hop onto this ledge from the initial entry point, start near the wall, not the edge.)

Nchuand-Zel Control
When you enter this zone, there is an alcove on either side, after which the passage turns left then right before climbing a ramp. At the bottom is a pressure plate that triggers a poison dart trap fired from both sides. At the top is a Falmer you can see, and another farther back to the right that is hidden from view. At the top, the passage turns left and extends away in front of you. Partway along is another pressure plate that triggers a spear trap from above, and at the far end are two more Falmer. On the left, near the Falmer, is a stone table with an apothecary's satchel, a random two-handed weapon, four loose gold coins, and various metal items on top, and an unlocked chest beside it. The passage turns left here, revealing the body of Staubin, the last of the mages on the expedition, with his diary. Beyond his body, the passage opens into a large room containing a Dwarven spider. There are stairs to the east that lead up. As you start to climb, several Dwarven automatons will appear from scuttles both ahead and at the bottom of the stairs. Once they have been dealt with, continue climbing counterclockwise. You will eventually find a Falmer fighting a Dwarven sphere. Wait for one to kill the other, then take on the survivor alone. In the southeast corner, the room continues through a gap in some metal grating, with a short flight of stairs opposite. Continue up these stairs to find a table with a Falmer bow, two Falmer arrows, a leveled potion of healing, and a lever that reactivates the automated defenses; pulling the lever also opens a gate behind you and updates the quest. To the right is an unlocked chest. Through the open gate is a walkway with another unlocked chest at the end. This walkway is directly above the first passage in this zone; when ready, simply drop down and exit through the door you initially entered through.

Exiting back to Nchuand-Zel
On exiting back to the main room, a battle will be underway; the first thing you will see is the centurion now active and fighting some Falmer. To your left is a column you can use to hide behind and let them battle it out. It's also a good position from which to take on the centurion, which nearly always wins its battle against the Falmer, if you wish. The abundance of Falmer usually results in them winning most of the other battles raging around the room. Deal with them as you see fit, and you're done. To avoid fighting completely, there is a ledge to the left of the door from Control which will take you back to the walkway at the start.

Notes
There is enough scrap metal in Nchuand-Zel to make almost 400 Dwarven metal ingots.
Nchuand-Zel has a small number of mini-Falmer that appear after the automated defenses have been turned on during the Lost Expedition, when the player returns to the chamber. They are about 60 percent of the size of their normal brethren, but just as powerful.
If you stop just short of pulling the final lever, after 60 days (the test point, although 30 should be enough), the items (Dwemer loot, potions, mines, etc.) will reset in some sections, but not others. The named dead NPCs' bodies will be removed.
In the Excavation, the ordinary spiders will not reset, but Nimhe, the dead Legionnaire soldier, loot, and ore veins will reset. (You may have to mine these on the return, since there is a glitch where ore veins don't always reset correctly.)
In the Main Chamber, the Falmer will not reset, but the loot will, as well as the chest on the south ledge accessible through the Quarters section. 
In the Quarters, the Falmer will reset, but not the loot or chests.
In the Armory, the Falmer, loot, and chests reset.
In the Control, the Falmer will reset, but not the loot nor the Dwarven spheres. The final treasure will still be intact.
Nchuand-Zel also appears in ESO.

Bugs