The Mausoleum of the Western Han Emperor, Liu Qi, is located at Zhanjiawan Village, about 20 kilometers (12 miles) north of Xian City, Shaanxi Province. It is a joint tomb of Liu Qi, a notable emperor of the Western Han Dynasty (206 BC-220AD), and his empress, Empress Wang. It was built in the year 153 AD and covers an area of 20 square kilometers (4,942 acres). It is a magnificent and abundant cultural relic, comprising the emperor's tomb, empress' tomb, the south and north burial pits, ceremonial site, human sacrifice graveyard and criminals' cemetery. The mausoleum is neatly arranged, centered with the emperor's tomb, revealing the strict hierarchical social structure. The Outside Pits Exhibition Hall was opened in 2006 and is the first underground museum in China.