In a series of firsts, the U.S. had sent State Secretary John Kerry to Hiroshima in April 2016, and he had said there the memorial was a "stunning" and "a gut-wrenching display." A month later, Barack Obama is set to be the first American president in office to visit the Hiroshima memorial. 

Both Obama and Kerry talked about the complexities of war and the choices made by leaders during one. They also acknowldeged victims of World War II. 

Obama's visit to Hiroshima, he was quoted as saying by CNN, was meant to highlight the "very real risks" of nuclear weapons. 

Hiroshima was the first city to be attacked by a nuclear weapon and the U.S. was the first country to use one. The A-Bomb dome is a symbol of "peace city" Hiroshima. Before the attack it was used as Hiroshima's Prefectural Industrial Promotion Hall. 

Also read: US President Barack Obama to make historic visit to Hiroshima

Today, the memorial is a reminder of the long-drawn suffering of the victims who survived and the 140,000 people who died on Aug. 6, 1945, and on succeeding days. 

Hiroshima
The gutted Hiroshima Prefectural Industrial Promotion Hall (R), currently known as the Atomic Bomb Dome or A-Bomb Dome, is seen after the atomic bombing of Hiroshima, Japan, on August 6, 1945, in this handout photo taken by U.S. Army in November, 1945,REUTERS/U.S. Army/Hiroshima Peace Memorial Museum/Handout via Reuters
Hiroshima
The gutted Hiroshima Prefectural Industrial Promotion Hall (C), currently known as Atomic Bomb Dome or A-Bomb Dome, is seen near Aioi Bridge in Hiroshima after the atomic bombing of Hiroshima, Japan, on August 6, 1945, in this undated handout photo taken by Toshio Kawahara and released by his grandchild Yoshio Kawamoto. MandatoryREUTERS/Toshio Kawamoto/Yoshio Kawamoto/Handout via Reuters
Hiroshima
Destroyed houses and buildings are seen after the atomic bombing of Hiroshima, Japan, on August 6, 1945, in this handout photo taken by Shigeo Hayashi in October 1945 and released by the Hiroshima Peace Memorial Museum.REUTERS/Shigeo Hayashi/Hiroshima Peace Memorial Museum/Handout
Hiroshima
Survey team members measure residual radiation in the ruins of Shima Hospital, located at the hypocenter of the atomic bombing of Hiroshima on August 6, 1945, as Japan Film Corporation staff film them in Saiku-machi district in Hiroshima, Japan, in this handout photo taken by Shigeo Hayashi in October 1945 and released by the Hiroshima Peace Memorial Museum.REUTERS/Shigeo Hayashi/Hiroshima Peace Memorial Museum/Handout via Reuters
Hiroshima
A picture shows the wreath U.S. President Barack Obama laid at a cenotaph at Hiroshima Peace Memorial Park in Hiroshima, Japan May 27, 2016.Reuters
A picture shows the wreath U.S. President Barack Obama laid at a cenotaph at Hiroshima Peace Memorial Park in Hiroshima, Japan May 27, 2016.Reuters
Present day Hiroshima
Japanese demonstrators protest against U.S. President Barack Obama and Japanese Prime Minister Shinzo Abe visiting Hiroshima, in front of the Atomic Bomb Dome at the Peace Memorial Park in Hiroshima, Japan May 26, 2016Reuters
Woman prays before Hiroshima memorial
Kinuyo Ikegami, 84, prays in front of the cenotaph for the victims of the 1945 atomic bombing, at Peace Memorial Park in Hiroshima, Japan May 27, 2016.Reuters
Hiroshima now
A man prays in front of the cenotaph for the victims of the 1945 atomic bombing, at Peace Memorial Park in Hiroshima, Japan May 26, 2016 a day before U.S. President Barack Obama and Japanese Prime Minister Shinzo Abe arrive in the city.Reuters
Obama at Hiroshima
U.S. President Barack Obama (L) and Japanese Prime Minister Shinzo Abe deliver speeches in front of the atomic bomb dome after they laid wreaths to a cenotaph at Hiroshima Peace Memorial Park in Hiroshima, Japan May 27, 2016.Reuters