As I head from the main road towards Dushnikh Yal http://img.photobucket.com/albums/v487/Lerf1950/Skyrim/2012-09-06_00002.jpg as I reach the bridge looking across the river I can clearly see a doorway. http://img.photobucket.com/albums/v487/Lerf1950/Skyrim/2012-09-06_00001.jpg

However, as soon as I get near it, this is all I see: http://img.photobucket.com/albums/v487/Lerf1950/Skyrim/2012-09-06_00003.jpg

There isn't anything showing on the compass as being near there, and I don't think it's a hidden rear entrance to anyplace.

Does anyone else see the same door or know what it is?

(I've seen it since I first took the road, long before I got Dawnguard, so I don't think it's anything to do with that.)