Could just be that I'm missing something glaringly obvious here, but, I've taken the Royal Door quest, I have King Godd's symbol, and my journal is telling me that all I will need to open the Royal Door and continue the game. But when I get to the door, where my gold quest marker is pointing me, it tells me the door in reinforced and cannot be opened. I figured I would just need to select the item in my inventory or something, but, I can't select it or perform any actions with it. So, is there something simple I'm overlooking here, or have I run into a bug?

I'm having exactly the same issue, so at least now I know there's at least one person as numb as me!!

Same here.  And I was having so much fun this weekend, too. :(

Try going back to town, deactivating that quest and then reactivate it and see where the arrows lead you.  I did something like that, and the arrows eventually pointed me a slightly different route to the same tower (coming up from the south)...

What a hindrance! Also impressed that google led me back home, thanks all!