Heart of darkness: once the world's most notorious jail, Hoa Lo Prison was the site of some of the worst atrocities in Vietnam's history. Minh Quang investigates the former "Hanoi Hilton"

Vietnam Investment Review, November, 2004 by Minh Quang

Hidden from the bustle of Hanoi, a squat building made of thick yellow stone sits on a small path connecting Hal Ba Trung and Ly Thuong Kiet streets.

The structure looks as unthreatening as it does nondescript, offering few clues--except for the imposing black door, which locals have dubbed the "monster's mouth"--about the litany of horrors that once took place within its walls.

Yet it was here that hundreds of Vietnamese communists and nationalists were held during the French colonial period, crammed into dank cells with tiny windows that allowed precious little sunlight. The prisoners' feet were ...