Hoan Kiem Lake, or the Lake of the Restored Sword, is located directly in the centre of Hanoi. The name is derived from a legend involving Emperor Le Thai To, in which he came across a giant tortoise while cruising on the lake. The tortoise took his sword that had secured victory against the Chinese aggressors of the Minh Dynasty. The emperor named the lake after this episode.
Every morning, the surrounding park fills with locals who arrive to exercise and play badminton. By the way, there still are a few tortoises who call this area home.