Halls of Lôrn

It is located far to the east of Bravil, near Fort Redwater.
 

Exterior
The exterior is located at coordinates: Tamriel 45, -16
This location's map marker is named Halls of Lôrn (editor name BANHallsOfLôrnMapMarker). The main entrance door is east of the marker, 150 feet away. The second entrance is north of the marker, 75 feet away.

Zone 1:
The entrance opens into a long hall. Go straight down the hall and through the door at the end of the right wall. Go up the stairs and through the gate into a large room with several doors. Most of these just open into small rooms, but the one in the north corner (to your lower right as you enter), which is locked, is a trap - it leads to a deep shaft. The one you want is in the eastern corner (to the left of the trapped door as you face it). This leads to the next zone, Halls of Lôrn, Arena.

Occupants: Mephalists

Treasure: Miscellaneous clutter

Traps: A door that leads to a deep shaft (see above).

Doors and Gates:
There are three doors in/out of this zone:
Two doors at the entrance lead to the West Weald.
One door leads to Halls of Lôrn, Arena.
One door (Novice lock) leads to a deep shaft.

Zone 2:
The door to this zone opens at the end of a large hall. Go down the hall and take the right-hand exit; go up the stairs, through the open space behind the chairs to your left, then up the stairs again. Follow the passage around until you come to a door; this leads to Halls of Lôrn, Arena.

Occupants: Undead, 1 storm atronach, Mephalists

Doors and Gates:
There are three doors in/out of this zone:
One door leads to Halls of Lôrn.
One door leads to Halls of Lôrn, Hall of Arcane.
One door leads to Halls of Lôrn, Arena.

Zone 3:
Depending where you came from, you'll either be in a hallway or at the bottom of a set of stairs. Either way, you need to go down to the floor of the large hall and find the passage behind the stairs. About halfway along, you'll find a pair of switches guarded by another Mephalist. Kill him and turn the switches; these will unlock the doors out of this level (one at the end of each hallway). Both doors go to the same hallway; a door at the bottom of the stairs leads to the final zone, Halls of Lôrn, Hall of Arcane.

Occupants: Mephalists

Doors and Gates:
There are three doors in/out of this zone:
One door leads to Halls of Lôrn, Hall of Arcane.
Two doors lead to Halls of Lôrn, Mage Wing.

Zone 4:
The goal in this zone is simply to get to upper platform in the center of the hall to chase Oron through a portal. You can accomplish this by going around the tiers, using stairs to ascend.

Occupants: Mephalists, Oron

Doors and Gates:
There are two doors in/out of this zone:
One door leads to Halls of Lôrn, Arena.
One portal leads to Third Sphere. The portal disappears once you have used it.

Zone 5:
The Third Sphere is a small part of an alternate dimension.

Doors and Gates:
There is one door out of this zone:
One portal leads to Blackwood.

The following areas are part of a separate section of the Halls of Lôrn, accessible at a later time. The entrance is in the same cell as the previous entrance, slightly north of the map marker, on the river bank.

Zone 6:
This level is pretty straightforward - make your way to the bottom. Once there, kill the two Mephalists guarding the arch and go through the door to the next zone.

Occupants: Mephalists

Doors and Gates:
There are two doors in/out of this zone:
One door leads to Blackwood.
One door leads to Halls of Lôrn, Lower Suburbia.

Zone 7:
Another easy level. Beware the vents spewing gas from the ceiling; there's one row near the door, and another at the far end, which is also guarded by a huge minotaur. You don't have to kill him - just run past him into the passage, and he can't follow. There are a few Mephalists down here, so keep on guard. All but one of the doors in this passage teleport to another door in the same level; the one you want is , which leads to the next zone, Halls of Lôrn, Crypt.

Occupants: Minotaur, Mephalists

Doors and Gates:
There are two doors in/out of this zone:
One door leads to Halls of Lôrn, Lower Subpassage.
One door leads to Halls of Lôrn, Crypt.
Several more doors teleport you to another door in the same zone.

Zone 8:
Follow the hall straight until you come to an intersection - a hall leading to the right. Take this one and go straight through, killing any Mephalists you encounter, until you come to a large shrine holding The Book of Rites. Take the book, backtrack to the first hall, and turn right. Go all the way up the stairs until you reach the door, which goes back to Halls of Lôrn, Lower Subpassage. You'll be at the end of a secret passage; activate the pressure plate to open the door, then make your way back up to the exit.

Occupants: Mephalists

Treasure: The Book of Rites

Doors and Gates:
There are two doors in/out of this zone:
One door to Halls of Lôrn, Lower Suburbia.
One door to Halls of Lôrn, Lower Subpassage.