The ‘Tribute in Light’ memorial shines two lights where the Twin Towers once stood.Visitors leave flowers, flags and photos at the National 11 September memorial in New York.Visitors to the 9/11 memorial read the names of the 2977 victims of the attacks.A collection of front pages in the 9/11 Gallery of the Newseum in Washington DC.A sign stencilled into the Arthur Ashe Stadium court acts as a memorial during the US Open.