A 15-year long-term plan to preserve a key 3,000-year-old archaeological site in the southwest of Beijing was publicly released on Wednesday by the Beijing Municipal Administration of Cultural Heritage.

Liulihe site in Fangshan district, found in the 1940s, can be dated the time of the vassal state of Yan during Western Zhou Dynasty (c.11th century to 771 BC), and is generally considered by academia to be the origin of the city of Beijing and a crucial discovery for the ritual system in Western Zhou.

According to the new plan, which guides relevant work until 2035, the protection zone will expand to 11.6 square kilometers from the current 7.1 square kilometers, within which urban construction will be strictly controlled. An archaeological park for public visit will also be built for further archaeological study and better promotion of the site's significance.

Ancient city ruins, a workshop site, graveyards and abundant varieties of bronzewares, including the biggest ancient bronze ritual artifact ever excavated in Beijing, have been discovered in Liulihe. In 1988, it was listed as a national-level key heritage site.