They are indeed. And the awful irony is that the moment that those snivelling cowards flew those aircraft into the towers, causing the loss of so many innocent people, Concorde G-BOAF was triumphantly completing a simulated LHR-JFK test flight, (LHR-LHR) readying for her return to commercial service after the Paris crash. This aircraft was completely full of Concorde people (myself included) and our absolute elation after landing turned into total despair as we all heard the terrible news from New York.
Im sure that all crews can still remember lining up on 31L for T/O, the stunning view of that amazing skyline crowned with the majesty of the World Trade Center. (Centre spelled the American way out of respect).
As has been mentioned above, two lost and sadly missed icons; The WTC & Concorde, inexorably and eternally linked.