The Walls Unit is the common name for the Texas State Penitentiary at Huntsville, the state's first enclosed penitentiary for convicted felons, opened in 1849. The name comes from the large brick walls surrounding the facility. Death row was located here from 1928 to 1965, when they were moved to the nearby Ellis Unit. The death chamber is still located here.
The café wall illusionis an optical illusion, first described by Richard Gregory in 1973. According to Gregory, this effect was first observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael's Hill, Bristol. This optical illusion makes the parallel straight horizontal lines appear to be bent.
The Walls of Jericho are well known because of this passage, Joshua 6:1-7, in the Hebrew Scriptures: Now Jericho was tightly shut because of the sons of Israel; no one went out and no one came in. And the LORD said to Joshua, "See, I have given Jericho into your hand, with its king and the valiant warriors. And you shall march around the city, all the men of war circling the city once. You shall do so for six days. Also seven priests shall carry seven trumpets of rams' horns before the ark; then on the seventh day you shall march around the city seven times, and the priests shall blow the trumpets. And it shall be that when they make a long blast with the ram's horn, and when you hear the sound of the trumpet, all the people shall shout with a great shout; and the wall of the city will fall down flat, and the people will go up every man straight ahead."