Built on wooden piers out over the tidal waters of Hiroshima Bay, Itsukushima Shrine appears to float at high tide — a deliberate illusion maintained since the original shrine was founded in 593 CE. The vermilion torii gate standing in the sea is one of Japan's most photographed images, and with good reason. At low tide you can walk out to its base.
The shrine complex (admission ¥500) includes several halls connected by covered walkways and corridors built at water level. Beyond it, the island itself is worth exploring — deer wander freely, the hillside temple of Daishō-in is rich with stone lanterns and Buddhist imagery, and Mount Misen can be reached by ropeway for wide views across the Seto Inland Sea.
Getting there: take Hiroden Line 2 to Hiroden-miyajimaguchi (about 70 minutes from the city centre), then the JR/Miyajima ferry (10 minutes, ¥200 each way). The Hiroshima Visiting Area Pass covers this entire journey.