In the picture you can see the Itsukushima Shrine's Treasure Hall. To access it you have to pay an extra fee.
The Miyajima island is one of the most beautiful spots in all Japan. In order to make the most of your visit, I recommend coming here first thing in the morning and leaving late in the afternoon. The island has some hotels. If you stay on Miyajima you will enjoy the views of the shrine by night, when its lanterns are lit.