Necropolis Hideout (Location)
A bandit camp in the Green Mountains – you'll do a thorough sweep of the locale during The Good Roman side quest.
Enter the above the aqueduct camp, and climb up the water fall.
You'll find yourself a the bottom of a great well. Climb out of this too, aiming for the wooden landing above.
There may be bandits up top, though not on guard. Safest to take them out anyway.
Head east, until the tunnel opens up.
One of the Hideout captains is stationed atop the platform here. Decomission him.
There's one other legendary-looking warrior here- deal with him as you like.
Loot the room, then head through a doorway south.
Smash the pot to the right of a small table to reveal a secret passage.
Shimmy through to loot the location treasure here- a carbon crystal.
Exit and head west to the hanging tree, disposing of one guard along the way.
Keep heading west, toward the civilians. This cave houses the prison, and there's a lot going on here.
But first, take out the two hostiles, one likely on ground level, the other up on the balcony.
Go up to the balcony. On the desk here is a letter which triggers the Taking Liberty side quest.
While you're here, you can also free the prisoners, but they tend to run uphill, right into the bandit camp, so you may want to clear that first.
The camp itself is heavily guarded, but not overly exciting.
The last treasure is in the middle of the ruin, in a red box. You can kill your way there, or cause a distraction (freeing the animals, or the prisoners, or setting something on fire are all proven go-to's).
The commander tends to hang out in front of an alternate entrance to the cave, at the south side of the ruins. There's a line of bushes in the yard above perfectly designed to aid a stealthy approach.
Dropkill from the ledge to seal the deal.
His death completes the location.