Why couldn't they simply have left a door in the wall?

He had found a low door in the wall of time.

A door in the wall led into a second room.

The little door cut in the back wall is about three feet high.

I turned around and put my face in the wall.

And the break in the wall was quite near too.

That may have been why they were used in the Wall.

She led him to a small window in the near wall.

There was only one other door to the room, in the far wall.

And, they had a new window in the other wall.