The national flag of Cambodia in its present form was originally adopted in 1948 and readopted in 1993, after the Constituent Assembly election in 1993 and restoration of the monarchy.

Since around 1850, the Cambodian flag has featured a depiction of Angkor Wat in the center. The current flag, with a blue border and red central (the stripes are in the ratio 1:2:1) was adopted following Cambodia's independence in 1948. It was used until 9 October 1970, when a new flag was introduced for Lon Nol's Khmer Republic that lasted until the takeover of the Khmer Rouge in 1975. The subsequent state of Democratic Kampuchea, which existed from 1975 to 1979, used a red flag with a three-towered Angkor Wat design retained in yellow beginning in 1976. The People's Republic of Kampuchea was established in 1979, after the Vietnamese invasion of Cambodia.

In 1993, the 1948 Cambodian flag was readopted. The current Cambodian flag, together with the flag of Afghanistan, hold the distinction of being the only two state flags to feature a building. Red and blue are traditional colors of Cambodia.

The flag used today is the same as that established in 1948, although the older flag is sometimes said to have used a red outline for Angkor Wat while the current flag uses black specifically.

More Info: en.m.wikipedia.org