Wall, Wall

Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into room, or protects or delineates a space in the open air. There are three principal types of structural walls: building walls, exterior boundary walls, and retaining walls.

More to the point, if an exterior structure is made of wood or wire, it is generally referred to as a fence, while if it is made of masonry, it is considered a wall. A common term for both is barrier, convenient if it is partly a wall and partly a fence, for example the Berlin Wall. Another kind of wall/fence ambiguity is the ha-ha which is set below ground level, so as not to interrupt a view yet acting as a barrier to cattle for example.

Since they are no longer relevant for defense, such cities have grown beyond their walls, and many of the walls, or portions thereof, have been torn down, for example in Rome, Italy and in Beijing, China. Examples of protective walls on a much larger scale include the Great Wall of China and Hadrian's Wall. A modern functional example was the Berlin Wall, which divided East and West Berlin.

The ground surface or water on one side of a retaining wall will be noticeably higher than on the other side.

A wall may also separate apartment or hotel walls from each other. Each wall has two sides and breaking a wall on one side will break the wall on the other side.

Source: Wikipedia > Wall