Criterion (4) : The mausoleum of Qin Shi Huang is the largest preserved site in China. It is a unique architectural ensemble whose layout echoes the urban plan of the capital, Xianyang, with the imperial palace enclosed by the walls of the city, themselves encircled by other walls. This capital of the Qin (to which succeeded on the present site of Xian the capitals of the Han, Sui and Tang dynasties) is a microcosm of the Zhongguo (Middle Country) that Qin Shi Huang wanted both to unify (he imposed throughout the land a single system of writing, money, weights and measures) and to protect from the barbarians that could arrive from any direction (the army which watches over the dead emperor faces outward from the tomb).