Located on Miyajima in the Seto Inland Sea, Itsukushima Shrine with its famous gate (torii) that appears to be floating on the water is one of the canonical Three Views of Japan. The part about its floating needs to be taken poetically, or perhaps seen under the right meteorological circumstances, but even just standing in the water the gate makes for an impressive, mysterious sight.
The gate and the shrine, built like a pier in the water, were created to allow pilgrims to approach but not set foot on Miyajima, which was held sacred in Shintoism. Later, when the island was inhabited, births and burials were still forbidden on the island. (Apparently there is still no hospital or cemetery on Miyajima.)