I have several comic book and video game related posters, as well as maps of the provinces of Skyrim, Cyrodiil and the Vvardenfell portion of Morrowind on my wall. Because I am a mature 30 year old adult and obviously this is what goes in my apartment.
I also have a map of my hometown (because it is the best place in the world and if you disagree you are wrong) as well as a couple of posters from theatre productions I helped with in university.
How about everyone else?