Hoan Kiem Lake means "Lake of the Returned Sword". The lake is the heart of Ha Noi capital. There is a legend about the name of this lake The lake is considered the center of Hanoi, not only physically but also symbolically. In fact, the more you spend time learning about the lake, the more special it becomes.

The tale goes that a King came across a shining metal bar when he visited his friend. It turned out that his friend caught the bar in one of his attempts for fish. The King asked for the bar, brought it home and moulded it into a sword. All of a sudden, there was two words printed on the sword “Thuan Thien” (harmonious with heaven). The King then understood that the sword was a gift from heaven. He used it for the battle against the war with China. 

Cái này hả ? :vv