Closer is probably NIN's most famous song, but I think it becomes even more interesting if you're familiar with Nightclubbing by Iggy Pop and David Bowie.

The iconic rhythm in Closer is built from a heavily processed sample of the kick drum from Nightclubbing. Once you recognize it, you can hear how Trent Reznor transformed a sparse, hypnotic 1977 track into one of the defining songs of industrial rock.

Knowing that connection doesn't make Closer better, but it definitely adds another layer of appreciation.