The Phra Si Ratana Chedi anchors the west end of the upper terrace. It was built by Rama IV in the mid nineteenth century at the same time as the Royal Pantheon. The chedi essentially balances the structures on the upper terrace, but it also recalls the monumental pagodas of the old capital in Ayutthaya. The chedi is faced with small gold mirrored tiles, making it a bit shinier than other pagodas that are 'just' gilded. The chedi houses a piece of the Buddha's breastbone.