The sound artist Andreas Bick got permission from the Jewish Museum in Berlin to record the room tones of its purposefully claustrophobic Holocaust Tower. He’s posted the resulting drones and ambient noise at his website, silentlistening.wordpress.com (MP3).
By leaving the microphone in the space, he not only captured its inherent sounds, but also those of passersby, at least one of whom was intrigued by the recording equipment. Writes Bick:
Finally you hear the steps of a visitor approaching the recorder who was attracted by the red and yellow LEDs in the dark. He ran into my microphone, put it back in place and left the tower immediately, passing me by with a somehow sorrowful expression on his face. I thought if I would have to desribe the German guilt complex towards the holocaust, it would have looked somehow like that.
More on the museum at jmberlin.de.