The West Gate

I'm pretty sure this will be taken as a sign that I've read too much Tolkien, but my first thought when I saw this small arch shaped rock formation?  "That looks like Durin's door, the west gate of Khazad-dûm."  (Translation: a magically-sealed arched-rock door into a long abandoned underground city built by dwarfs, one of whom was named Durin.) 

I was tempted to wait for moonlight to see if the special mithral inscription would show up.