The arch database has been updated several times as a lot of work is currently ongoing with it. It has 811 arches (826 including false arches), 484 of which are on the maps. Check them out on the Arches Map.
You can check them all out on my favorite site feature, the Landform Map, which has everything on it!
If you know of something not on the map, something that is incorrect, or you have a picture to add to a landform, please SUBMIT HERE.