The sad end of it all
I was not even two yet, when the towers fell. I was in New York City, on 20th Street in Manhatten, not so far from the WTC. My mom went to pick up my sister when they heard the towers were struck (my parents were telling me this recently) and when my mom retured, the towers had fallen. It turns out, someone from my sister's school was ON one of the flights that crashed into Twin Towers.
Now this is not meant to be silly or anything like that, but railfanning would never be the same. Higher security, more police officers, and even us railfans getting arrested near high populated areas. You can't even railfan in GCT (Grand Central Terminal) without being questioned by the police (I wasn't probably because I'm a kid). Whenever I go railfanning on the Hudson Line I'll aim for a low populated area not close to NYC.
I remember a couple years ago me and my dad would take the PATH to New York, and I was about six and on the train, my dad said, "Thats where the Twin Towers were." The tunnel was still cut open from the attack, and all you could see were giant pits where the twin towers were. And that was the sad ending, riding passed some giant pits which is where I could've seen two massive towers.