Đống Đa (lit. 'Banyan Heap'; Vietnamese pronunciation:[ɗəwŋ˧˥ ɗaː˧˧]) is one of the four original urban districts (quận) of Hanoi, the capital city of Vietnam. It is bordered by Ba Đình to the north, Hoàn Kiếm to the northeast, Hai Bà Trưng to the east, Thanh Xuân to the south, and Cầu Giấy to the west. The district currently has 21 wards, covering a total area of 9.95 square kilometres (3.84 sq mi). It is the most populous district in Hanoi. As of 2017, there were 420,900 people residing in the district, the population density is 42302 inhabitants per square kilometer, 18 times higher than the overall density of Hanoi. Dong Da district is home to various enterprises and many of Vietnam's most prestigious universities such as Hanoi Medical University, Foreign Trade University, University of Transport and Communications, Thuyloi University.

Dong Da district has a large number of monuments and relics, including Temple of Literature (Văn Miếu), a cultural symbol of the city. The district is also where the Battle of Ngọc Hồi-Đống Đa between Tây Sơn dynasty and the Qing dynasty, one of the greatest victories in Vietnamese military history, ended.

Đống Đa is located at 21°00' North, 105°49' East, in the center of Hanoi. The district covers an area of 9.95 km (3.8 sq mi), bordered by Ba Đình to the north, Hoàn Kiếm to the northeast, Hai Bà Trưng to the east, Thanh Xuân to the south, and Cầu Giấy to the west. Of the land in Đống Đa, 5.00 km (1.93 sq mi), or 50.3% is specially used land, while 4.36 km (1.68 sq mi), or 43.8%, is used for residential purposes.

Đống Đa has relatively flat terrain, with only a few small mounds in the eastern parts, including Đống Đa Mound.

There are several large lakes such as Ba Mau lake, Kim Lien lake, Xa Dan lake, Dong Da lake, Van Chuong lake. In the past, there used to be many ponds and lagoons; however; but due to social-economic development and urbanization, the number of them has been reduced, with many being filled or polluted.

• Ba Mau Lake
• Dong Da Lake
• Hao Nam Lake, near Cát Linh station of Line 2A, Hanoi Metro
• Nam Dong Lake
• Van Chuong Lake
• Linh Quang Lake
• Khuong Thuong Lake
• Ho Me Lake, located at the corner of the street Ton That Tung - Truong Chinh, next to the Hanoi Medical University
• Lang Lake
• Kim Lien Lake

The district is divided into 21 wards (phường).

Văn Miếu Quốc Tử Giám Hàng Bột Nam Đồng Trung Liệt Khâm Thiên Phương Liên

Phương Mai Khương Thượng Ngã Tư Sở Láng Thượng Cát Linh Văn Chương Ô Chợ Dừa

Quang Trung Thổ Quan Trung Phụng Kim Liên Trung Tự Thịnh Quang Láng Hạ

As of 2015, there are 11169 acting enterprises, cooperatives, and 11133 non-farm individual business establishments in the district. Several of Vietnam's largest companies, such as Petrolimex, Vinacomin, Vietnam Posts and Telecommunications Group, Vietnam Steel Corporation and VPBank, are headquartered in this district.

• 
  Lang Road
• 
  Thai Ha Street
• 
  Pham Ngoc Thach Street
• 
  Nguyen Chi Thanh Street
• 
  Truong Chinh Street
• 
  Tay Son Street