One World Trade Center was built as the main building of the new World Trade Center complex, after the original complex was destroyed the September 11 attacks in 2001. When rumours came around that the World Trade Center was to be rebuilt, architects denied the rumours and called the building the Freedom Tower, but then confirmed the rumours. The building's construction started in 2006 using stronger steel girders and glass. The building uses a asymmetrical pyramid design, meaning that it looks like it ascends into a pyramid when viewed from street level.