Completed in 1591 but destroyed in the atomic blast, Hiroshima Castle was reconstructed in 1958. Its five-story wooden donjon is a faithful reproduction of the original, but the main reason to come here is the very good museum housed in the castle's modern interior, which can be toured in about 30 minutes. The museum is devoted to Hiroshima's history as a flourishing castle town, with good English-language presentations. It also gives the best description I've seen on castles in Japan, including differences in architecture between those built on hills (for defense) and those built on plains (mainly administrative). Videos (with English translations via earphones) describe Hiroshima's founding and the construction of Hiroshima Castle, while displays explain the differences in lifestyle between samurai and townspeople, the hierarchy of the feudal administration system, and other aspects of Edo life. There's also samurai gear, models of old Hiroshima and the castle, and, for children, a kimono and samurai outfit they can try on. The top of the donjon provides a panoramic view of the city.