Hiroshima was the first city I visited outside of the Tokyo/Yokohama area, way back in late April. I took an overnight highway bus that arrived around 8 in the morning, packed my luggage in a locker, and started my exploration of the city.
several plants that survived the atomic bomb, and at least some have reproduced.
You can visit Peace Park and the surrounding memorials/surviving buildings in a full morning. While it's a very sad reminder of the destruction mankind does to itself (and America did to Japan), I feel visiting these sites was important to understand what happened and Japan's view of the event. It's interesting to see how much Hiroshima has really recovered as a city and grown around the park, when many thought the area would be inhabitable for decades.
Peace Park is 15 minutes from Hiroshima Station on tram line 2 or 6 (150 yen ride). Admission to the museum is 50 yen and it's open from 8:30 AM until 5, 6, or 7 pm depending on the season. All other locations shown here are free.