Built in 1958 as a memorial to Cambodia’s war dead and to celebrate independence from foreign rule, the monument stands majestically on the intersection of Norodom Boulevard and Sihanouk Boulevard in the centre of the city. It is designed by the influential Cambodian modern architect Vann Molyvann in the form of a lotus-shaped stupa in the same style seen at the great Khmer temple at Angkor Wat and other Khmer historical sites. The monument consists of five tiers decorated with 100 Nagas and is most impressive in the late afternoon hours when the sun casts shadows over the sculptures.
Cambodia celebrates Independence Day on 9 November each year. The Independence Monument, already one of Phnom Penh’s most significant structures, becomes even more celebrated when His Majesty King Norodom Sihamoni leads the annual jubilation by ceremoniously lighting a giant torch placed inside the monument in front of a huge spectator of high officials from the government, private sectors and members of the Cambodian public.
source : http://www.tourismcambodia.org/