Hiroshima, and the one building left standing near the hypocentre

At a quarter past eight on the morning of 6 August 1945, an American bomber dropped the first atomic bomb used in war over the centre of Hiroshima. It exploded some six hundred metres above the city. The blast, the heat and the fire that followed destroyed most of the city within a radius of a couple of kilometres, and an estimated 140,000 people had died by the end of the year, from the explosion itself, burns and radiation sickness. Many thousands more died in the years that followed. Three days later, a second bomb fell on Nagasaki. Within a week, Japan had announced its surrender.

Hiroshima today is a busy, modern city of more than a million people, rebuilt on the same river delta, with wide boulevards, trams and a lively centre. That is the first surprise for many visitors, who expect something more scarred. The memory of the bombing is concentrated in one place, at the heart of the city, and it is handled with extraordinary care.

The Dome

On the bank of the Motoyasu River stands the most recognisable of the very few structures that survived near the hypocentre, the point on the ground directly below the explosion. It was built in 1915 as the Hiroshima Prefectural Industrial Promotion Hall, designed by a Czech architect, Jan Letzel, with a green copper dome, and it was used for exhibitions of local products. The bomb exploded almost directly overhead, and because the blast came from above, parts of the walls remained standing while the people inside were killed instantly.

After the war, there was a long debate about whether to demolish the ruin or keep it. The city decided to preserve it exactly as it was, with the bare steel frame of the dome and the broken walls, reinforced against collapse. It is now known as the Atomic Bomb Dome, or Genbaku Dome, and it was inscribed as a World Heritage Site in 1996, as a symbol of the destruction and of the hope for peace. It is not possible to go inside. Seeing it from the riverbank, with ordinary city life going on around it, is quite enough.

The Peace Memorial Park and Museum

Across the river, on a delta island that was once a busy commercial district, lies the Peace Memorial Park, designed by the architect Kenzō Tange. Its main axis runs from the museum through an arched cenotaph, which holds the names of those who died, and across a pool to the Dome beyond. The Flame of Peace burns in the middle, and is to be kept alight until nuclear weapons are abolished. The Children's Peace Monument commemorates Sadako Sasaki, a girl who developed leukaemia from the radiation, and the thousands of folded paper cranes left there by schoolchildren from all over Japan and the world.

The Peace Memorial Museum tells the story of the bombing through personal possessions, photographs and the testimony of survivors, the hibakusha: a child's charred lunchbox, a melted watch stopped at 8.15, scraps of clothing. It is a hard museum to go round, and it is meant to be. Most people come out quieter than they went in. Leave time to sit in the park afterwards.

The rest of the city, and Miyajima

It would be a mistake to see Hiroshima only as a memorial. It is also a city that likes to eat, and its own style of okonomiyaki is a local passion: a savoury pancake built up in layers on a hot griddle, with cabbage, noodles, pork and egg, then brushed with a thick, sweet sauce. The castle, rebuilt in concrete after the war, has a museum of the city's earlier history.

A short journey away is Miyajima, the island of the great vermilion torii gate that stands in the sea in front of the Itsukushima shrine, one of the best-known views in Japan. Most tours pair the two, and the contrast between the morning in Hiroshima and an afternoon on the island is part of the day.

G Adventures' Discover Japan, thirteen nights in October to December, includes Hiroshima and Miyajima on a route from Tokyo and Lake Kawaguchiko through Kanazawa, Takayama and Kyoto.

Explore Worldwide's Highlights of Japan, seven nights, includes Hiroshima and Miyajima with Tokyo, Nagano and the snow monkeys of Jigokudani, Kanazawa, Osaka and Kyoto. G Adventures' Japan: Castles and Cuisine, five nights, is a short trip that covers Kyoto, Hiroshima, Miyajima Island and Osaka.

Few places anywhere ask so much of a visitor in a single morning. It is worth going.