The Cot Co (Flag Tower) is part of the Hanoi Citadel (plus the Vietnam Military History Museum) and its one of the symbols of Hanoi. It was built in 1812 as a later addition to the Hanoi Citadel, which was built by Emperor Gia Long with help from French engineers in 1805. The Cot Co Flag Tower is approximately 33.4 meters tall and contains a 54 step spiral staircase.
