Engineers who responded to Ground Zero after 9/11 reflect on the collapse of the Twin Towers, the World Trade Center recovery effort, and the structural engineering lessons that reshaped New York City. Subscribe to TIME’s YouTube channel ►► ti.me/subscribe-time Subscribe to TIME: ti.me/3E3UCqt Get the day’s top headlines to your inbox, curated by TIME editors: ti.me/48dFNwQ Follow us: X (Twitter): ti.me/3xTVwSk Facebook: ti.me/3xWI2Fg Instagram: ti.me/3dO9Rcc 0:00 September 11, 2001: The 9/11 Attacks Begin 4:06 Remembering 9/11 at the World Trade Center 5:16 What Structural Engineers Do 6:58 The Engineering History of New York City Skyscrapers 7:41 How the Twin Towers Were Engineered 10:42 Engineers Witness the World Trade Center Attacks 12:38 Structural Engineers Mobilize at Ground Zero 15:23 Search and Rescue at Ground Zero 21:28 Assessing Buildings Damaged by the Twin Towers Collapse 27:16 The Ground Zero Slurry Wall and Hudson River...