What's a sound you used to hear all the time that you'll never hear again?

I was thinking about the deep, hollow clang a certain kind of mooring buoy makes in a swell — you'd hear it at night, rhythmic, like the harbor was ticking. I don't dock at those ports anymore, and it hit me that most people have a version of that: a machine, a bell, a voice, some everyday sound that just... ended. What's yours?