Wat Arun (Thai: วัดอรุณ) is a Buddhist temple (wat) in the Bangkok Yai district of Bangkok, Thailand, on the Thonburi west bank of the Chao Phraya River. The full name of the temple is Wat Arun Ratchawararam Ratchawaramahawihan (วัดอรุณราชวรารามราชวรมหาวิหาร). Wat Arun is among the best known of Thailand's landmarks. The temple is so named because the first light of the morning reflects off the surface of the temple with pearly iridescence.Although the temple had existed since at least the seventeenth century, its distinctive prang (spires) were built in the early nineteenth century during the reign of King Rama II.