I was at the office when the first plane hit, and a little later at home as I watched in horror on live-TV how the twin towers came down in a storm of dust. My children still recount the look on my face.
We visited the former location of the WTC, the holes it left in the new square at the foot of the freedom tower, and the new museum. The museum was very well done: with a well dosed amount of respect, anger and documentation. And I should add, without the American patriotic sentimentality you sometimes see in exhibitions like these (in our cynical European eyes).
The above sketch is Ladder 3, the firetruck that was wrecked by the collapsing towers.
And the burned and bent remains of one of the steel columns of the facades. It makes you realise the magnitude of the forces during the events.
Well worthy a visit. But come early, before the crowds arrive.