What city, the tower from the photo is a symbol?

The Flag Tower of Hanoi (Vietnamese: Cột cờ Hà Nội) is a tower in Hanoi, Vietnam, which is one of the symbols of the city and once a part of the Hanoi Citadel, a World Heritage Site. Its height is 33.4 m. The tower was built in 1812 during the Nguyen dynasty as an observation post to the Hanoi Citadel. It is now located in the Vietnam Military History Museum