The 34th Street/Herald Square subway station is the closest to our apartment, so naturally, it's one of the stations that I visit most frequently. It wasn't until we'd been living here for about a year, though, that I noticed the big green rectangular racks hanging between the signs that say which way the train is headed.
Anyone who thinks to reach a hand way up above his or her head (okay, maybe it's just me, I'm short!) and set off the motion sensors will be rewarded with a loud musical note that sings in the hustle and bustle of the station. And every time I reach my hand up there and "play" a note, people turn and stare because they had no idea that the green "instrument" was even there. And there's another one on the opposite side of the station, too!
It's apparently all an art installation by Christopher Janney called, "REACH: New York, An Urban Musical Instrument" and has been there since 1996, largely unnoticed from what I can see. Its creator intended for it to be an interaction among strangers on the platform who would play the notes together.
But no one ever plays with me! So all you readers out there have to help me spread the word, okay? :)