I want to be careful not to overstate what it means for a building to die. A building’s worth is an infinitesimal fraction of the worth a person’s life. Even two buildings don’t even move the needle in comparison to real human loss. But a building is still a living thing in a way. It breathes and it moves. This movement makes a sound.

Les Robertson, the structural engineer of the World Trade Center, says that the people working inside the tower couldn’t feel this movement, but they could hear it.

This episode of 99% Invisible was produced with the Kitchen Sisters, Davia Nelson and Nikki Silva, and the creaking “Buildings Speak” section was mixed by Jim McKee of Earwax Productions. It’s comprised of extracts and outtakes from the Peabody Award Winning “Sonic Memorial Project” produced in 2002. A new, tenth-anniversary edition of the Sonic Memorial Project, which is narrated by my literary hero Paul Auster, is going to be playing on public radio stations around the country. Find out where and when it’s playing on your local public radio station and make an appointment to listen.