Hồ Gươm

Hoan Kiem Lake (Vietnamese: Ho Hoan Kiem, meaning "Lake of the Returned Sword" or "Lake of the Restored Sword", also known as Ho Guom) is a lake in the historical center of Hanoi, the capital city of Vietnam. The lake is one of the major scenic spots in the city and serves as a focal point for its public life.
According to the legend, emperor Le Loi handed a magic sword which brought him victory in his revolt against the Chinese Ming Dynasty back to the Golden Turtle God (Kim Qui) in the lake and hence gave it its present name (the lake was formerly known as "Luc Thuy" meaning "Green Water"). The Tortoise Tower (Thap Rua) standing on a small island near the center of lake is linked to the legend.
Large soft-shell turtles, either of the species Rafetus swinhoei or a separate species named Rafetus leloii in honor of the emperor, have been sighted in the lake. The species is critically endangered and the number of individuals in the lake is unclear.

Source : en.wikipedia.org/wiki/Hoan_Kiem_Lake