Notre Dame Cathedral, also known as the Cathedral of Phnom Penh, was a 19th-century French Gothic revival church that served as the cathedral of the Apostolic Vicariate of Phnom Penh. It was located in the Russei Keo District of the city on Monivong Boulevard.
The construction of the cathedral began in the 19th century and was overseen by the French colonial government in Cambodia. The architectural style has been described as resembling Reims Cathedral. Shortly after the Khmer Rouge conquered Phnom Penh at the end of the Cambodian Civil War, the cathedral was destroyed.
In 1863, Cambodia became a protectorate of France within its colonial empire. Construction of the cathedral most likely started after this time. It was built near the riverfront of the Mekong and was situated at the heart of Phnom Penh on the Monivong Boulevard in the Russei Keo District, a few blocks away from Wat Phnom. A Bishop's Palace and a church library were built adjacent to the cathedral, which was hailed as an "architectural legacy of the French" by The New York Times.
The grounds of the cathedral was the site of the Russei Keo refugee camp from May 1970 onwards. It harboured 10,000 refugees from North Vietnam who were displaced by the Vietnam War. In October 1972, intense fighting between the Khmer Republic and the Khmer Rouge during the Cambodian Civil War commenced outside of the capital city. One incident resulted in two Khmer Rouge rockets landing behind the cathedral. However, nothing serious arose from the incident. Another similar rocket attack occurred in January 1974. This time, the rectory of the cathedral was damaged.