As part of the effort to protect Beijing 's historical relics, the Ming Dynasty (1368-1644) City Wall Relics Park opened in 2002. The ancient city wall park follows the opening of the Huangchenggen Relics Park in September 2001, also known as the Imperial City Wall Relics Park , in downtown Beijing . The one-kilometre-long Ming Dynasty city wall relics is said to be the last existing part of the third ring of the ancient city wall, which stretches from Chongwenmen to Dongbianmen in eastern Beijing. To make way for the park encompassing 13 hectares (32.12 acres) of land, residents in 1,800 households had to leave. The park cost a whopping 850 million yuan (US$102 million) to build, a large portion of which was used to compensate residents who had to move. More than 120,000 ancient city wall bricks have been collected in the past three years to rebuild the section of the city wall, which dates back to the 14th century. Beijing was once surrounded by four rings of city walls: the Forbidden City wall, the Imperial City wall, the inner city wall and the outer city wall. Broad ring roads were built in the 1950s and 1960s, but the third and fourth rings of the city wall had to be sacrificed.