What structural design changes do you propose to make skyscrappers crash-proof?

Alright!

I'm a complete newbie to structural engineering fundamentals and I'm sorry if the question is too basic.

I believe it's an important one. One of the news channel just explained how the north & south tower of World Trade Center did not collapse because they got hit by the airplanes. They said there were bombs in the buildings that got the building down.

Now, I may not believe what the news channel say. I'm thinking; what are the structural design changes that can be implemented in skyscrapers to make them crash-proof?