What was weird was that I guessed that the first plane crash wasn't an accident and that being that there were two extremely prominent towers the second one would get hit later that morning as part of a coordinated terrorist attack. So, when the second plane hit I wasn't in the least bit surprised. I wasn't even that surprised that the U.S. had been attacked given that it had spent 50 years making enemies around the world in its dumb fight against Communism. The fact that both buildings collapsed so suddenly when the Empire State building has survived being struck by an aircraft years earlier was really just a testament to the shoddy workmanship of the 1970s. I later saw a documentary where this fact was confirmed by one of the World Trade Center's construction engineers who had complained at the time they were being built that the fire-retardant coating wasn't covering everywhere it should in the internal lattice of the superstructure, but then that's Capitalism for you.
Of course, this isn't meant to suggest Communism is better. They are both extremes. The U.S.S.R. has had a lot of its people die in earthquake zones in buildings that were constructed out of poorly mixed concrete, that would have otherwise have survived. In their case, people weren't given any incentive to do the job properly so botched it. Personally, I think the U.S. is slightly worse here as it was deliberate cost-cutting not laziness.
By the way, OP, I don't think that you should say that "Al-Queda allegedly hijacked 4 airliners" as there were reports that Osama had a guest over listening to the radio and the guest was very pleased when the plane crashed into the first tower. However, bin Laden said words to the effect:"wait... there's more" which has been recorded on tape, so he must have had knowledge of the second plane ahead of time. Linking the pilots to al-Qa'ida and from this "global terrorist network" back to its "mastermind" Osama, is a bit too far-fetched and James Bond for me - in a way Bush's Axis of Evil has just done this loose affiliation of malcontents a big favour where they can blow up a Bali nightclub and then say it is the work of al-Qa'ida and ride the coat-tails of the elaborately coordinated "one-off" 9/11 attack (which I'm confident was only as spectacular as it was because the airport security was lax at the time, the FBI watching the foreigners train as pilots didn't intervene when they could have done and whoever planned it knew that security would ramp up hugely afterward - so: better make it as big as possible; I don't know that al-Qa'ida ever need to try to replicate or surpass this attack, so the whole Department of Homeland Security, War on Terror, illegal invasion of Iraq and hunt for Osama in the caves of Afganistan turning into a protracted policing mission is all just a bunch of willy-waving to make the outgoing Republicans look manly and spread enough fear amoungst the U.S. people they worry about that more than their failing economy or their lack of basic healthcare.