At the heart of Hanoi, both literally and figuratively, is Hoan Kiem Lake. Although just one of many parks and lakes in Hanoi, Hoan Kiem is the most important. The lake lies just south of the old ancient part of town, and is the center of a sort of Arthurian legend. According to this legend, in the fifteenth century a fisherman found a magical sword in his nets one day, and he presented it to Emperor Ky Thai To (also known as Le Loi). The Emperor used the sword to defeat the invading Mongols. One day after the battle, the Emperor was enjoying an afternoon boat ride on Hoan Kiem Lake when a giant golden tortoise appeared, took the sword and disappeared into the depths of the lake. The restoration of the sword is the subject of one of the skits performed by the water puppets.
The Tortoise Pagoda in Hoan Kiem Lake
A small pagoda sits on an islet in the center of the lake, and is dedicated to the tortoise. The lake is surrounded by a narrow strip of park-land with paths leading all around. There's a small café at the southwest corner of the lake which is almost always crowded when the weather is nice. Near the northeast corner of the lake a red wooden bridge connects to a small island with the Ngoc Son Temple on it.
A pair of friends enjoying the sunset
The park around the lake is popular all day long. In the morning, you'll see people exercising, while in the afternoon people walk, sit and enjoy the sunset, or meeting special friends to watch the sunset.
At the northeast corner of the lake, across the road that rings the lake, is the main theater for seeing one of Hanoi's other "must see" sights, the water puppets.