The path brings you right up to the wall of the tower, but there's no door in sight. You press your hand on the wall, it doesn't budge. It feels like cold, solid stone. Then you notice a small engraving. It's faded, but after a little dusting off you can see it's an arrow bent in a full circle. There's no text that you can see.
The glowing message remains illuminated. You get the feeling it's waiting for you to read it and do something.
You return to the front door of the tower. You wonder if it's only open for you, or if you've opened it for everyone. You haven't seen any other travelers around, so maybe it doesn't make a difference.