Approximately in the middle of the mountain range between the Castle and the Troll Island lies an entrance to a derelict metro system. There are some pretty strong "Vagrants" inside, 350 EXP each. They attack on sight. Deeper inside what looks like a fairly complex base of theirs the loot happens to show the "Steal.." markers. This indicates these vagrants don't need to be an enemy, or that the area is a part of some quest or something. But how, what, from where? Does anybody know?
you'll move through it as part of the Albs main questline and can optionally clear it out for a reward from the clerics
Before or after actually joining them?