The One Pillar Pagoda is one of the oldest and most important temples in Vietnam, and is the symbol of Hanoi As its name suggests, the pagoda is built upon a single pillar, designed to resemble a lotus flower blooming from a small square pond.
The lotus is a symbol of purity in Buddhism, and the temple's design relates to the legend of its history. Long ago, the Vietnamese emperor was lonely and childless. One night he had a dream that a Bodhisattva (something like a Buddhist saint) brought him a white lotus upon which a small child was sitting.
Later, the emperor fell in love with and married a peasant girl who gave him a son. To celebrate and memorialize the occasion, as well as to offer thanks, the emperor constructed the One Pillar Pagoda in honor of the lotus flower from his dream.
You can visit the One Pillar Pagoda when you visit Ho Chi Minh's Mausoleum and the Presidential Palace, as it's nearby both of those famous Hanoi landmarks.
You must dress properly when visiting the pagoda, as it is a Buddhist temple and Vietnamese holy site. No sleeveless shirts, and no shorts are allowed for women.
The pagoda is located just outside Ho Chi Minh's Mausoleum, and between the Presidential Palace and the Ho Chi Minh Museum. Admission is free.