《北史·本记·卷七》
下诏征召民夫一百八十万人修建长城，从幽州北面的夏口开始，西到恒州，长九百多里。
诏发夫一百八十万人筑城，自幽州北夏口，西至恆州，九百余里。
An imperial edict was issued to conscript 1.8 million civilians to build the Great Wall, starting from Xiakou in the north of Youzhou and stretching 900 miles west to Hengzhou.