One day
Begin at the Peace Memorial Park — the A-Bomb Dome, the cenotaph and the Children's Peace Monument — and give the Peace Memorial Museum the time it deserves. Have a Hiroshima-style okonomiyaki lunch downtown, then see Hiroshima Castle and the Shukkeien Garden in the afternoon, riding the streetcars between them. End with dinner and oysters (in season) in the Nagarekawa district.