This day, 61 years ago, was the single most destructive day in human history. On August 6, 1945, at 8.16am, an atomic bomb exploded 600 metres above Hiroshima. An intense sun-like energy carbonised and flattened the city centre and tens of thousands of people died in an instant.
You arrive in the city knowing some of this. You leave knowing a lot more. But in between, it's mostly as if the bomb was never dropped. For Hiroshima is a pleasant, modern and prosperous city, surrounded by mountains and lapped by the waters of the Seto Inland Sea between the Honshu mainland and Shikoku, going about its business in perfect tranquillity.
And so there are two Hiroshimas: the peaceful contemporary one that is there all around you, and the horrific A-bombed one in your mind. Strangely, there seems to be no connection - they are distinct places and the historical one fades fast from consciousness.
Built anew, unblemished save for the preserved ruin of 'the A-Bomb Dome', and far bigger and wealthier than the city of old, Hiroshima is the ultimate phoenix. As you explore the attractive metropolis and its natural surroundings, the power of the present is paramount.
An efficient bus and tram system moves you around easily. There are several city attractions worth visiting, such as the rebuilt castle, which rises out of a great moated compound, and modern art museums with their Henry Moores and French impressionists. But the real treats are at the ends of the lines.
Bus No22 terminates at Mitaki-ji Temple, which clings to a wooded hillside amid tumbling waterfalls. At this shrine of verdant nature and myriad deities, dotted with wooden pavilions and pagodas, you stroll up shady trails past scores of carved stone monuments and little jizo statues with cute red bibs and woolly hats. When you learn these guard the spirits of dead, perhaps aborted, children and were probably put there by their mothers, their comic effect turns to heartbreak. A hidden side of modern Japan is revealed in a deeply traditional setting of stunning beauty.
Another easy ride takes you to one of Japan's most scenic, age-old icons. At the end of the No2 tram line, a ferry takes passengers across to Miyajima Island, where, in the blue waters, stands a huge curved-lintel torii gate the colour of a red-hot poker. This is the formal entrance to the ancient Shinto temple of Itsukushima, the gateway from the temporal to the spiritual realm. It is revered as one of the 'three views of Japan', the country's most picturesque sights.
The thickly wooded island, which is a sacred and protected site, is dotted with shrines and is home to deer that are completely tame, if not downright blase. At low tide, the torii gate is left stranded, towering over a hive of activity as hordes of cocklers sift the muddy beach and fill buckets with fresh shellfish.
Trams No1, 3 and 5 end up at the port, from where ferries chug out to the many islands of the Inland Sea. Among these local escapes, quaint Ninoshima Island is a favourite, its mountainous contours laced with walking and cycling trails.
Further ripostes to Hiroshima's image as a place of overwhelming sadness are the friendliness of the people and its reputation for having excellent sake and a good-time culture that produces rollicking Saturday nights. The city is said to have 4,000 bars. If you go on a pub crawl in the gaudy grid of streets in the Nagarekawa entertainment district, that claim seems entirely plausible.
While Hiroshima exercises its right to a normal life, it never forgets that fateful August day in 1945. The city authorities are fully committed to an anti-nuclear weapons agenda and to fostering international peace and understanding. The Peace Memorial Park, built at the tip of an island just south of the A-bomb target point, makes this clear. Hiroshima is on a delta where a river heading for
the Inland Sea splits into seven channels; it is a city where you are constantly crossing waterways. A
T-shaped bridge connecting three banks was chosen by the Americans as a distinctive point to aim for in the heart of the city. To replace the wooden buildings, including a temple, which crowded this vicinity and which vanished that day, the Peace Park was built to commemorate the dead and to inform and inspire the living. Planted with a wide variety of trees and shrubs, the park is home to many monuments and shrines. Here, as was intended, you are in both Hiroshimas.
Deeply moving and rich in meaning, each feature has its own style: the Buddhist Peace Bell with its heavy wooden ramrod; the grassy Memorial Mound containing the ashes of thousands of unidentified people, like an old imperial mausoleum; the Children's Peace Monument, with its multicoloured strings of paper cranes; the Stone Lantern of Peace; the eternal Flame of Peace; and many more. But they coalesce into one anti-war message. Hiroshima suffered such a horrendous tragedy that its people, it seems, are profoundly pacifist.
But it's only when you walk through the Peace Memorial Museum that you truly know why. Here,
in graphic detail, with photographs, models, surviving objects, films and many other aids, the whole story is clearly told. Most affecting is the waxwork tableau of scorched, ragged, wild-haired people staggering through a fiery hell, their melted skin hanging from their pathetically outstretched arms.
At the exit, there is a visitors' book, heavily endorsed, containing little but Japanese. I feel at a loss. What can one possibly write? Suddenly, it is obvious, two words: 'Never again!' But as for visiting Hiroshima again, I'd love to go back. It is green, airy and scenic and it has a feeling of life valued through losing so much.
Getting there: Kansai is the nearest airport for flights from Hong Kong, operated by Cathay Pacific (www.cathaypacific.com ), ANA (www.anaskyweb.com ) and Japan Airlines (www.jal.com ). Trains to Hiroshima take about 90 minutes. See www.pref.hiroshima.jp  and www.jnto.go.jp  for more city and regional information.