The Hanoi Citadel, also known as the Imperial Citadel of Thang Long, is a historic site located in Hanoi, the capital of Vietnam. It served as the political center of the country for over a millennium, from the 11th century until the 19th century. The citadel features ancient architecture, including the Flag Tower and remnants of royal palaces, reflecting the rich history of the Ly, Tran, and Le dynasties. Designated a UNESCO World Heritage Site in 2010, the Hanoi Citadel is an important cultural landmark. It showcases various artifacts and structures that highlight Vietnam's historical significance and architectural evolution. Visitors can explore its grounds to learn about the country's past and appreciate its heritage.