Photo taken on Jan 13, 2017 shows a basement excavated at the site of the ancient town of Yueyang in the Yanliang district of Xi'an, capital of Northwest China's Shaanxi province. [Photo/Xinhua]

Chinese archaeologists have unearthed a rare basement and fireplace in the ruins of an ancient city that served as a state capital some 2,400 years ago.

The five-meter-long and four-meter-wide room was built nearly one meter below ground at the ruins of Yueyang city, capital of the Qin state during the Warring States Period from 476-221 BC Stone pillar bases and square bricks were also found in the room.

Renowned archaeologist Li Yufang said buildings with basements were rare during that period, denoting an upscale style and indicating the ruins were actually the residential palace of the state ruler.

Experts surmised the basement was a storage room for the belongings of the ruler's concubines.

A fireplace -- a feature only seen in residential palaces of rulers during the period -- was also found at the ruins, said Liu Rui, a researcher with the Institute of Archeology of the Chinese Academy of Social Sciences and head of the excavation team.

The remains of Yueyang city are in the district of Yanliang in Xi'an city, Shaanxi province in Northwest China. It served as the capital of the Qin state for 35 years.

A famed political reform took place in the city about 2,300 years ago, when Qin statesman Shang Yang initiated a series of reforms that led to the foundation of China's legal system. His reforms are believed to have made Qin the strongest state during the tumultuous period, paving the way for Emperor Qinshihuang to build the Qin Dynasty and unite China in 221 BC.