If the Chinese wall was built by Chinese why loopholes are turned towards China?

Dmitry, the wall was built to defend enemies from the north. If you visited the wall, you would find that "loopholes" you referred were built on each side of the wall. It's convenient for the soildiers to observe and shoot their enemies.

See, their enemies were from the north. Standing on a higher postion is much more helpful. The soldiers could find and kill their the enemies easily. As the attackers, the enemies used the ladder to conquer the wall from the north.