《管子·八观》
内城的城墙不可不坚固完整，外城的四周不可有外通的空隙，里的边界不可以左右横通，闾门不可不注意关闭，院墙与门日不可不注意整修。
大城不可以不完，郭周不可以外通，里域不可以横通，闾闬不可以毋阖，宫垣关闭不可以不修。
The inner city walls cannot but be strong and complete, the outer city cannot have any gaps for outside communication, the boundaries inside cannot have horizontal access, the lattice door should be noted to be closed, and the courtyards and gates should be noted to be repaired every day.