It had to happen sooner or later - claims that the World Trade Center was poorly built and exploited loopholes to get planning permission. But it is difficult to ignore the source of the criticism: RIBA Gold medallist Harry Seidler. He says he visited the construction site and could not believe the design and the flimsy materials being used, and claims that the Empire State Building and Sears Tower would have withstood similar airliner impacts. 'I can tell you that these two skyscrapers were an absolute exception, ' 78-year-old Seidler tells the Austrian newspaper Kleine Zeitung . 'I was incredibly surprised at the time that the construction was so delicate. It's the lightest thing I ever saw. I was almost speechless when I saw the elevator shafts and staircases were lined with plaster. They told me they were fireproof. The World Trade Center was little better off than if it had been built out of cardboard sheets. With most buildings, the steel supports are coated with concrete; in the WTC they were only coated with plaster. The steel supports were only sprayed with asbestos, and in the heat which developed, it's as soft as spaghetti. That's a terrible way of building. He points out the towers were commissioned by the Port Authority of New York: 'They built on their own property, and at the same time issued all the permits to themselves. The whole thing was a matter of cost.'