Tokyo, Japan (CNN) -- U.S. Ambassador John Roos will make a historic appearance Friday at Japan's Peace Memorial Ceremony in Hiroshima.
His will be the first time in 65 years that an American ambassador has attended the ceremony, which marks the atomic bombing of the city by the United States in 1945.
"At this particular point, we thought it was the right thing to do," said U.S. State Department spokesman P.J. Crowley last month.
Roos will join U.N. Secretary-General Ban Ki-moon and other dignitaries at the Hiroshima Peace Memorial Park, where victims of the bombing will be honored and prayers for world will be offered.
More than a million people flock to Hiroshima's peace museum every year.
At 8:15 a.m. on August 6, 1945, the U.S. B-29 bomber Enola Gay dropped an atomic bomb named "Little Boy" over the city of 350,000 people.
Hiroshima, situated 426 miles (686 kilometers) southwest of Tokyo, was charred and leveled beyond recognition.
Some 140,000 people died in the attack.
Another 70,000 died when U.S. forces dropped another atomic bomb on Nagasaki, 593 miles (954 kilometers) southwest of Tokyo, three days later.