I've noticed that there are sometimes symbols on homes... walls... castle walls... it seems like......... they're usally like... right next to a door to go a loading screen.
Anyone know what they're for, or why they're there. Their placement is obvious, and random.

I've seen these on pretty much every single building I've encounters, even some old empty shacks in the woods. Could be a ward or some kind of protection... or maybe it is simply a house address number...?

I saw one on a sewer system wall

Without wanting to do too much spoiler wise: it has to do with the thieves guild. Theres a book on it.

Information for theives

I think that is a fantastic detail to have in the game and instantly reminded me of early to mid 20th century "Hobo sign code" indicating houses to other itinerants where they might be able to earn a meal doing chores, or warning them away from places they wouldn't be welcomed.

An example of what I'm talking about, for those who don't know:

http://www.angelfire.com/folk/famoustramp/signs.html