..Just a quick input about the "implosion of WTC explosion". the Buildings were designed by Japanese Designer and aluminium was used for infrastructure and not steel and probably cause for the collapse because the aluminum melted at lower Fahrenheit than Steel.
So, never again, aluminum building. But who would have thought that there would be such a burning impact. I saw Michael Moore's video. Worth seeing if you want to be aware of the issues we will probably have to face in the next few months and years.
I believe that the Sears tower in chicago has been quietly upgraded in the last couple of years due to it's somewhat similar "exoskeleton" design.