Making a 'wallpaper' out of photos

I was at a party once and the host had a bathroom where the walls were completely covered in a collage of photos and magazine clippings. It was 'sealed' with something over the top of them so they didn't peel or anything, very neat looking, so I was thinking about doing this myself.

I cannot find any resources that tell me a good way to go about this though, hoping someone here has some suggestions?

Thanks!

You can laminate them.