Phra Pathommachedi (Thai: พระปฐมเจดีย์) is the tallest stupa in the world with the height of 127 metres (417 ft). The temple which houses the stupa is Wat Phra Pathommachedi Ratcha Wora Maha Wihan (Thai: วัดพระปฐมเจดีย์ราชวรมหาวิหาร), located in the town of Nakhon Pathom, Thailand.
The name Phra Pathommachedi means Holy chedi (stupa) of the beginning. The stupa at the location is first mentioned in Buddhistscriptures of the year 675, however archaeological findings date back to the 4th century. In the 11th century it was overbuilt with a Khmer (Ancient Cambodia) styleprang, which was later overgrown by the jungle. The ruin was visited several times by the later King Mongkut during his time as a monk, and after his coronation he ordered the building of a new and more magnificent chedi at the site. After 17 years of construction it was finished in 1870, and the population of nearby Nakhon Chai Si was ordered to move to the newly created town around the chedi.