Rattanakosin Island is a historic area in the Phra Nakhon District in the city of Bangkok, Thailand. It is bordered by the Chao Phraya River to the west and various canals to the east that were dug to serve as moats for what was originally the fortified city center. Situated on the eastern convex bank of a meander in the Chao Phraya River, the island is the site of the Grand Palace and Bangkok's City Pillar Shrine, among other places of historical significance.