Phnom Kulen (Khmer: ភ្នំគូលេន), or Mount Mahendrapura, is a sandstone plateau considered sacred by the Khmers.
Located 28 km (17 miles) northeast of Angkor and 48 km (30 miles) from Siem Reap (about a 2 hour trip), the site is the mythical birthplace of the Cambodian Kingdom. In 802 CE Jayavarman II was crowned here, he declared himself chakravartin, meaning universal monarch, in a ritual taken from Indian Hindu tradition. The cult of the 'God-King' or Devaraja was established and the 500-year Angkor Empire began.
Jayavarman II built his first brick pyramid temple-mountain at Phnom Kulen to house a sacred golden linga dedicated to Shiva. Today, the temple is only visible in fragments but, over 1200 years later, the phallic emblem is still on display in the Phnom Kulen complex.
The Phnom Kulen temple is best known for its carved lintels and bas-reliefs. There are also some remains of ninth-century Cham temples in the area – I recommend having a guide to point them out as they are small and well concealed in the forest.
Also at the hill’s summit is the largest reclining Buddha in Cambodia, which is over 900 years old.
Phnom Kulen was at the centre of Jayavarman II's capital, Mahendraparvata, before he returned to Hariharalaya where he died later in the 9th century.