Firma degli operai che hanno contribuito alla realizzazione del grattacielo

NEW YORK, NY – JUNE 25: Construction worker John O’Shea signs the last steel beam, along with other members of the crews that helped build the tower, before it is hoisted 977 feet to the top of Four World Trade Center on June 25, 2012 in New York City. The trapezoidal glass and steel office building, which is designed as an architectural backdrop to the September 11 Memorial, is scheduled to open in 2013. (Photo by Spencer Platt/Getty Images)