Wall base issue

If you build a wall and tear it down so that the base is still standing, you can cross it. But if you leave the area where the wall was built and then re-enter, then you can no longer cross the base of the wall. If you hit the base of the wall with a hammer, you can cross the base. If you leave the area and enter it again, you cannot cross the base of the wall again. If you hit the base with a hammer several times, the base of the wall disappears. The vacated place, where the base of the wall was previously, can be crossed without any problems.

~Philosophjes