You arrive at the spot that Rashid marked on your map... it's at the mouth of a small canyon that you would normally ignore. As you go into the canyon, you see other tracks moving towards, what looks like, a pit. When you get closer, you see that earth has been moved away and a door is visible at the bottom of very worn and treacherous steps leading down. The door at the bottom is open, but only slightly... it looks to be made of granite and would require quite a feet of strength for someone to move without tools or magic.
(there is a door, I just couldn't find the right pic)