How do i keep my dog out of my room?

i need to stop my dog from peeing all over my room coz its the last room in the house that he needs to hit.. i usually close the door but somehow when i get back to my room someones opened it, and my family doesnt really seem to mind urine all over the house because hes cute so theyre jus letting him get away with it. i was considering getting a gate or a half door, but figured that that would look ridiculous indoors. Bare in mind that he is untrainable. Im sort of obsessive compulsive and last time he invaded my room it took me over an hour to clean it. any suggestions?