From the City of Hiroshima and the Agency for Cultural Affairs.
The building was designed by the Czech architect Jan Letzel and finished in 1915 as the Hiroshima Prefectural Commercial Exhibition Hall.
It was a three-story brick building. The center of the front was a five-story stair hall, topped with an oval dome.
It showed and sold products from the prefecture, and was also used for art shows and fairs.
At 8:15 a.m. on August 6, 1945, a U.S. B-29 bomber dropped the first atomic bomb in human history. It exploded 600 meters above the center of Hiroshima.
In an instant, buildings in the city fell down, and many lives were lost.
The hall was about 160 meters from the point under the explosion. It was badly broken by the blast and heat, and burned. Most of the walls of the second and third floors fell.
The Atomic Bomb Dome still stands much as it was after the bombing. It shows the terrible harm of nuclear weapons, and across time it calls for getting rid of nuclear weapons and for lasting world peace.
In 1992 the Hiroshima City Council asked for it to become a World Heritage site. People across Japan signed petitions. In 1995 the national government made it a historic site, and in December 1996 the World Heritage Committee, meeting in Mexico, added it to the list.
There is no single right answer. Talking it over with someone at home is a good way to learn.