The path down to the rubble is fairly easy, despite all of the bits of marble strewn about. The tower is floating about 100 ft. from the ground, just over the area you are walking toward.
When you get within about 50 ft. from the rubble pile itself, a dragonborn runs up to you with hands held up (seemingly in a gesture of surrender) and quietly says "Hail to you all! I heard fighting in the valley and feared that the undead had increased their numbers. I barely survived myself. They've boxed me into this forsaken place without food or water. Perhaps you can spare a little of both?"
The dragonborn points to the floating tower. "In return, I'll gladly share my temporary refuge...it's the only place the undead don't seem to go."