At the corner of State and Randolph, across the street from the Chicago Theatre, there's a disco ball that is not like other disco balls. It's resting on the sidewalk, for one, not hanging from a ceiling scattering light across a room. It's chained to an iron fence. And there's a headphone jack embedded in it. Plug in a pair of earbuds and you can hear a new song by Katy Perry that was just released exclusively via two dozen disco balls hidden in plain sight around the globe.

Wednesday morning (February 8), Perry tweeted a world map studded with disco balls and their approximate locations. Eleven cities in the United States got disco ball installations, including Chicago, whose ball was originally said to be in Wicker Park. The new Katy Perry song, apparently called "Chained to the Rhythm," was three CTA stops away. Obviously, I set out in search of it.

After searching the park to no avail and explaining my quest to a confused park district employee, I noticed the map had updated the Chicago ball's location to the Chicago Theatre, the stately movie theater turned venue in the city's downtown Loop. I hopped another train, walked a few blocks under the elevated rail, and arrived at the iconic marquee. The doors to the theatre were locked, and again there were no disco balls in sight.

About ready to pack up and call it a morning, I looked at my phone one last time. The photo on Chicago's geotag showed the disco ball in the bottom right corner — not inside or next to the Chicago Theatre, but across the street in front of the Old Navy. I darted over and found it: a full-size, honest-to-goodness disco ball next a small pink lawn sign bearing the hashtag #ChainedToTheRhythm.

Like Katy asked, I'd brought my own headphones to the impromptu listening station. I plugged them in, but the audio was cranked up so loud I was afraid they'd blow out, and this disco ball didn't come equipped with a volume dial. There was a pair of iPhone earbuds conveniently draped over the hashtag sign, so I swapped those out and found the music still loud, but listenable. Katy Perry's voice blared over a disco beat for a few bars, seemingly on loop, inexhaustibly.

The disco ball debut isn't the first time Katy Perry has embarked on an unconventional rollout. In 2013, she announced her LP Prism by hiring someone to drive a golden truck around with the album's release date printed on the side. But planting actual music in the urban wild is another gesture entirely, and one that artists rarely attempt now that streaming premieres are the easiest way to reach masses of simultaneous listeners.

Standing in the February cold listening to a disco ball through headphones is one way to feel like an alien in a sea of downtown commuters. Aside from a couple of other journalists who showed up for the same reason I did, no one in Chicago seemed to know the disco ball was there. Katy Perry's name didn't appear anywhere near the installation; you had to have seen her tweet to know that anything was playing through the headphone jack. And what played seemed to be a 45-second sample of "Chained to the Rhythm" on repeat — it didn't sound like a full song, although it could just be one of those tracks that's mostly chorus.

The most intriguing part of the disco ball treasure hunt wasn't meeting up with other listeners in my own city (though I did run into my friend Mike), but the idea that people around the world were searching for the same thing at the same time I was. Seeing photos of disco balls discovered in Miami and Raleigh was more fun than hearing what the disco balls were playing. Even seeing gag photos of headphones plugged into a colander brought a sense of communion. Simultaneously tracking down a wild disco ball with dozens of other song-hunters is an absurd and joyful idea all on its own. The song — or what we could hear of it — almost felt like a footnote.