If you look at the map you will see a road running from east to the west then north and back eastward. Follow this road until it ends and head north ward, you will come to it, eventually. Ariant is the big bridge - there is also a monument about half way down the bridge for a different deed. The key to this is that you have to get up on the bridge since you won't get it when you are underneath the bridge (which is the first place I went given the co-ords). Be-aware the whole area if full of mobs in the high 30's so bring some friends unless all the mobs are grey (below level). There are also some kind of big troll things on the bridge, I think they are elite. I was at lvl 65 and they were pretty easy to deal with but if I was alone and in the 40's it would not have been pretty