The school might not have a campus visit program for people who haven't applied yet, but you can always make contact with the program coordinator or equivalent, or the professor for a class you're interested in. It might make a difference to your admission, if you are on an unconventional path and some of the usual boxes might not be checked but you can at least sound like you know what you're talking about (I was an elementary ed undergrad, then recently finished a MA in math ed, now about to start a pure math MS program; I met with the grad coordinator this past spring to talk about prereqs, and by the end of the conversation he told me to hurry up and apply and he'd hang onto a TA position for me). Conversely, if you're looking at exceptionally selective schools, probably everyone makes early contact and if you don't you're putting yourself at a disadvantage.
Don't get stuck on the idea of touring the campus. It's a college, it has buildings and trees and parking places and grassy things and maybe a statue or two. The architectural style is really the least important thing.