Wat Phnom (Khmer: វត្តភ្នំ; “Mountain Pagoda”) is a Buddhist temple (wat) located in Phnom Penh, Cambodia. It was built in 1372, and stands 27 metres (88.5 ft) above the ground. It is the tallest religious structure in the city. The pagoda was given the name of Wat Preah Chedey Borapaut. Wat Phnom is the central point of Phnom Penh.
Legend relates that a wealthy widow called Penh (commonly referred to as Daun Penh – Grandmother Penh – in Khmer) found a large koki tree in the river. Inside the tree she found four bronze statues of the Buddha. Penh constructed a small shrine on an artificial hill made by the people living in the village to protect the sacred statues. Eventually this became a sacred site and sanctuary where people would make blessings and pray.
Then it came to the year of the snake 1437 suggests King Ponhea Yat ordered His Excellency Decho Srei to raise the mount even higher when he finished building the new Royal Palace in the new city he then named Krong Chaktomok Mongkol or simply known as Phnom Penh. The prominent stupa immediately west of the sanctuary contains the ashes of the king and his royal family.
Wat Phnom is the center of celebration during Khmer New Year, and Pchum Ben. source: wikipedia