Fort Clostra
A Roman Fort in northern Klysma Nome. You'll spend some time here during the No Chains Too Thick story quest.
Consider waiting for the story mission, and then just killing everyone here. You're going to have to carry at least one person through the camp, and the prisoners here are civilians, not rebels, who will tend to throw themselves on the nearest enemy weapon they can find.
Start by crossing the fence nearest to the execution site.
Assassinate the near guards, then make your way up and along the watchtowers.
Snipe/sneak-kill targets of opportunity, but try not to let loose until you've trapped the braziers (extra guards aren't really a threat to you, they're just tedious).
You can also use the central mounted crossbow- it does extremely impressive headshot damage.
The camp commander tends to hang out by (and sometimes behind) his tent on the south easterly edge of camp.
That same tent contains one local treasure in carbon crystal form
The other treasure is in a large tent just southeast of the crossbow tower, in a red chest.
The local captain likes to patrol the top of the hill, next to the tent where Tahira is being held.
Doing all this completes the location