Problem : A blank space on your wall & a picture too small to fill the aforementioned space
Solution : The Rasterbator!

OK, despite the juvenile name, the page linked to offers a free service. You supply the photo, they produce a multi-page PDF file you print out, and stick up on the wall.
As is so often true in life, it is the simple approach that wins the day. You can either use the service online, where you’ll need to keep the uploaded picture to a maximum size and resolution, or you can download the (still free) program, and run the process locally, on your own machine.

This post is NOT sponsored, I just liked the service, and thought people (especially John) might be interested enough to try it out. Let me know what you think.