The year 1989 came long before the digital revolution in film, so Rob Reiner didn't exactly have a ton of technological options when he pressed record. That means When Harry Met Sally was shot on good, old-fashioned 35mm—and it's got the classic look to prove it.
The most important aspect of When Harry Met Sally is that it was shot almost entirely on location. The exteriors shots of New York? That's no Vancouver-as-stand-in. Even the movie's first scene was actually shot at the University of Chicago. This authentic, on-location shooting helps lend a sense of realism to Harry and Sally's story. They feel like real people, walking around a real city.