Its just a maze. Jump over the lowered fences and make your way through the ruins (bottom featured picure), go through the doors, and then follow the maze starting on your left. You'll end up all the way on the right.
there's a grunt blocking the way to the cave
Continue walking right. Its in the bottom right of the cave.
how I do I get past the guy who is guarding the cave entrance?
1 task at a time, this is a 2-goal quest, fix the other part first and report back
