13 years after the attacks on September 11th, a new building has opened its doors where the Twin Towers of the World Trade Center once stood. 

This morning was a very different morning in New York City to that one over 13 years ago on September 11th. For the first time since then, today workers began arriving at the building now known as One World Trade Center, where they were opening up a new chapter in the life of one the world's biggest cities. 

The biggest of the first residents of the new building is Condé Nast, the folks behind magazines such as GQ and Glamour, and while it was simply another Monday for their workers, it was something a bit special to be turning up to the striking new edifice in the heart of Manhattan. It is now the tallest building in America at 1,776 feet tall (104 stories) and since 2006, when construction began, it has been a mammoth project to bring it together, costing in the region of $3.9 billion to complete. However, it has all been worth it, as this is now more of a symbol than it is a simple building. 

Watch some timelapses of the building being constructed below, and have a look through the gallery to see what the building is like, inside and out.