US President Barack Obama has taken a firsthand look at the skyscaper being built on the site of the World Trade Centre, in New York.
He was joined by first lady Michelle Obama, New York Governor Andrew Cuomo and New York City Mayor Michael Bloomberg.
Obama toured the construction site where he met some of the workers, before his party signed the final steel beams that will be installed as part of the building's framework.
The US president expressed his thanks to the project's workers, saying: "We couldn't be prouder of you guys, that is what the American spirit's all about, so congratulations."
The skyscraper will replace the twin towers that were destroyed in the September 11 2001 terror attacks.
The group also toured the 22nd floor of One World Trade Centre, walking along the unfinished cement floor, stopping at easels set up with renderings of what the completed tower and grounds will look like.
The skyscraper is expected to be completed by early 2014.