The name of the structure built to commemorate the First World War in London is the Cenotaph. Located in Whitehall, the Cenotaph serves as a war memorial dedicated to those who lost their lives during the war. It was designed by Sir Edwin Lutyens and unveiled in 1920. The monument features an empty tomb, symbolizing the absence of fallen soldiers, and is a focal point for national remembrance activities. Each year on Remembrance Sunday, ceremonies are held at the Cenotaph to honor the sacrifices made by military personnel in both world wars and subsequent conflicts, providing a space for reflection and commemoration.