The WTC was built to be indestructible, withstand Huge wind speeds, multiple fires and even JET crashes. The WTC twin towers were the jewel in the crown and were 110 floors, 500,000 tonnes, 200,000 tones of steel and 300,000 tonnes of reinforced concrete. Everything about the towers was massive, the towers were built with 3 times working loads in mind. A square steel outer cylinder with an “Indestructible” steel core was its construction. All other tall buildings followed and improved upon the WTC design style, it was the strongest, tallest structure of its day, a significant achievement using only the most high quality steel.