The Phnom Kulen National Park is a national park in Cambodia, located in the Phnom Kulen mountain massif in Siem Reap Province. It was established in 1993 and covers 373.76 km2. Its official name is Jayavarman-Norodom Phnom Kulen National Park.
During the Khmer Empire the area was known as Mahendraparvata and was the place where King Jayavarman II had himself declared chakravartin, an act which is considered the foundation of the empire.
General admission: $20
Wikipedia https://en.wikipedia.org/wiki/Phnom_Kulen_National_Park
More info at tourismcambodia.com http://www.tourismcambodia.com/travelguides/provinces/siem-reap/what-to-see/78_phnom-kulen-national-park.htm
Coordinates 13°36'18" N 104°6'15.289" E