It rises from a pond on a single concrete pillar, and is supposed to represent a lotus. It isn’t original—the French blew it up in the 1950s, and it was rebuilt.
My problem with Hanoi is that there are too many spots to be considered as the Number One, impossible to make decision, so let’s think that there is space for multiple #Ones. This Buddhist temple was known with name “Diên Hựu tự” which means “Long lasting happiness and good luck”.
The temple is located close to Ho Chi Minh mausoleum and I recommend taking a walking round from Old Quarter to the mausoleum and planning this spot to the route.
There’s of course a legend behind: “According to legend, one ageing Emperor, who had no children, used to go to pagodas to pray Buddha for a son. One night, he dreamt that Bodhisattva Avalokiteshvara, who was standing on a great lotus flower, gave the King a baby boy. Later Queen gave birth to a male child and the Emperor ordered the construction of a pagoda supported by only one pillar to resemble the lotus seat of his dream in the honor of the Bodhisattva Avalokiteshvara. There is a theory that the pagoda was built in a style of a lotus emerging out of the water”.