I live a 90-minute drive from Ground Zero, but never went in to see the site after 9/11. I drove around the tip of Manhattan once some months afterward on my way to or from somewhere, when there was literally nothing to see from the West Side Highway (I still call it that) but a wall. But I never went down to gawk. That's not to say I don't wish I had seen it once for myself, but I never did it, and I still haven't been there to see the new structures, etc.
As for the TOD in general: certainly 9/11, the JFK assassination, the Oklahoma City bombing, and in earlier days when I was active in flying, major plane crashes such as the DC-10 at O'Hare and the PSA/Cessna crash over downtown San Diego (these were in 1978/79). And the two space shuttle disasters. I'm no doubt forgetting some stuff at the moment, but those are the biggies.