The 3000 square metre permanent exhibitions tell the story of the Second World War and the Holocaust through personal objects including a birth certificate of one or the few babies to survive being born in a concentration camp and bullet casings dug out of the ground at the scene of a massacre.
Among the survivors at the museum on Monday was 84-year-old John Hajdu who was hidden as a child in Nazi occupied Hungary.
He worked with the museum to translate postcards from Hungarian into English including one sent by a mother to her son while she was being transported to her death in Auschwitz.
Mr Hajdu, who lives in Muswell Hill, said: “Miraculously she was able to take this postcard and put it out of the wagon and that somebody found that postcard and somebody posted that postcard to her son is an unbelievable story.”
He said: “It simply talks about how she is unlikely to meet her son again and this is an opportunity to say goodbye.”
The galleries includes more than 3,500 objects including a piece of wreckage of the USS Arizona which was sunk at Pearl Harbour and photographs of mass executions.
Also on display are dozens of objects loaned by members of the public including the last letter home from a kamikaze pilot and the body of a gerbil found by a soldier serving in Iraq who sent it to his sister as a joke.
The museum’s Director General Diane Lees said: “The Second World War and the Holocaust will soon pass out of living memory, leaving us without the first-hand testimony of veterans, eyewitnesses and survivors.
“IWM’s new galleries, which have been nearly six years in the making, will preserve their stories and ensure that the world never forgets what they experienced. With a recent YouGov poll demonstrating that 93% believe the Second World War and the Holocaust are relevant to learn about today and 78% think that genocide is currently happening in the world, the opening of these galleries has never been more significant.”
The galleries open their doors to the public on October 20.