The Ponhea Yat (ពញាយ៉ាត) stupa at Wat Phnom
Ponhea Yat was the last ruler of the khmer empire and the first king ruling Kampuchea/Cambodia from Phnom Penh.
The old khmer capital in Angkor Thom fell to invading forces from the former vasall state of Siam in 1434CE. After the destruction of the imperial city of the khmer god kings, the smaller kingdom needed an easier defendable city, closer to trade routes and waterways.
Names
After his new royal palace was completed, he gave the new capital the the name Krong Chaktomuk Serei Mongkol, 'City of the Brahma's Faces'. It refers to the four rivers that meets and flows in the capital region.
The two largest is the Tonle Sap river from the giant inland lake of the same name, and Mekong river flowing down from the Himalayas. They join forces in front of the Royal Palace.
The full name of the kings capital was Krong Chaktomuk Mongkol Sakal Kampuchea Thipadei Serei Theakreak Bavar Intabat Borei Roat Reach Seima Moha Nokor, translated loosely to "The place of four rivers that gives the happiness and success of Khmer Kingdom, the highest leader as well as impregnable city of the God Indra of the great kingdom"
Ponhea Yats capital was abandoned several times between 1494 and 1865. But king Norodom choosed Phnom Penh as his capital, and it has stayed capital since.
His remains are kept prominently in this stupa behind the pagoda at Wat Phnom, the central hill on the west riverside of Tonle Sap being the namesake and origin of the capital city.
From the stupa, there is a good view into the old french town of Phnom Penh, towards the Royal Palace in the distance.