A year into the biggest project of their career, a lost letter made the developers of 1 World Trade Center start from scratch. Vanity Fair has a preview of the new documentary 16 Acres, which chronicles the challenges and conflicts that surrounded the redevelopment of the iconic structure. Months after the cornerstone for 1 World Trade Center had already been laid, security concerns from the New York Police Department halted construction and forced a redesign of the entire project at a cost of $20 million. Seven months earlier, the NYPD had written up their security assessment in a physical letter and mailed it to the New York Port Authority, the tower’s co-developer. But the letter was lost, and the NYPD never followed up. Nearly a year later, they issued a confidential security report stating that the building would be too vulnerable to terrorist attacks.

The new security guidelines and required the building to be moved and redesigned. "In effect, we had to go back and come up with a new building," says Janno Lieber, who oversaw the planning and construction of the new towers. You can watch the whole documentary on Netflix now, and the film is coming out on DVD on May 20th.