The wall
Nehemiah 4:3
Now Tobiah the Ammonite was by him, and he said, Even that which they build, if a fox go up, he shall even break down their stone wall.
Psalm 62:3
How long will ye imagine mischief against a man? ye shall be slain all of you: as a bowing wall shall ye be, and as a tottering fence.
Isaiah 30:13
Therefore this iniquity shall be to you as a breach ready to fall, swelling out in a high wall, whose breaking cometh suddenly at an instant.