Dong Da is one of the four original urban districts of Hanoi, the capital city of Vietnam. It is bordered by Ba Dinh to the north, Hoan Kiem to the northeast, Hai Ba Trung to the east, Thanh Xuan to the south, and Cau Giay to the west. The district currently has 21 wards, covering a total area of 9.95 square kilometers. It is the most populous district in Hanoi. As of 2017, there were 420900 people residing in the district.