Young Blonde Girl With A Picture On The Wall

Before the invention of artillery, many of the world's cities and towns, particularly in Europe and Asia, had protective walls (also called town walls or city walls). In fact, the English word "wall" is derived from Latin vallum, which was a type of fortification wall. 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.
Separation walls
Some walls are designed to formally separate one population from another. An example was the Berlin Wall, which divided East and West Berlin.