This is the Wall of the Missing memorial at the Normandy American Cemetery and Memorial. It honors 1,557 U.S. service members who died during the D-Day landings and subsequent liberation of France but whose remains were never recovered or identified. There’s a video of the entire memorial under the Videos menu at the top of the page under 2022 France Videos, or you can go there now (opens in a new tab): 2022 France Videos.