The Underground City (Chinese: 地下城; pinyin: Dìxià Chéng), also known as Dixia Cheng, is a bomb shelter comprising a network of tunnels located beneath Beijing, China, which has since been transformed into a tourist attraction. It has been called the Underground Great Wall because it was built for the purpose of military defense. The complex was constructed during the 1970s in anticipation of a nuclear war with the Soviet Union, and was officially reopened in 2000. Visitors were allowed to tour portions of the complex, which has been described as "dark, damp, and genuinely eerie".