Defensive wall

A is a  usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications with towers, bastions and gates for access to the city. They are used to enclose settlements. Generally, these are referred to as s or s, although there were also, such as which extended far beyond the borders of a  and are used to enclose regions or mark territorial boundaries. In mountainous terrain, defensive walls such as are used in combination with castles to seal valleys from potential attack. Beyond their defensive utility, many walls also have important symbolic functions – representing the status and independence of the communities they embraced.

Existing ancient walls are almost always structures, although brick and timber-built variants are also known. Depending on the of the area surrounding the city or the settlement the wall is intended to protect, elements of the terrain such as rivers or coastlines may be incorporated in order to make the wall more effective.

Walls may only be crossed by entering the appropriate and are often supplemented with s. The practice of building these massive walls, though having its origins in prehistory, was refined during the rise of city-states, and energetic wall-building continued into the present era.

Simpler defensive walls of earth or stone, thrown up around s, s, early s and the like, tend to be referred to as or banks.

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