Defensive wall in the context of "Curtain wall (fortification)"

Edo Castle (江戸城, Edo-jō) is a flatland castle that was built in 1457 by Ōta Dōkan in Edo, Toshima District, Musashi Province. In modern times it is part of the Tokyo Imperial Palace in Chiyoda, Tokyo, and is therefore also known as Chiyoda Castle (千代田城, Chiyoda-jō).Tokugawa Ieyasu established the Tokugawa shogunate there, and it was the residence of the shōgun and the headquarters of the military government during the Edo period (1603–1867) in Japanese history. After the resignation of the shōgun and the Meiji Restoration, it became the Tokyo Imperial Palace. Some moats, walls and ramparts of the castle survive to this day. However, the grounds were more extensive during the Edo period, with Tokyo Station and the Marunouchi section of the city lying within the outermost moat. It also encompassed Kitanomaru Park, the Nippon Budokan Hall and other current landmarks of the surrounding area.

The walls of Constantinople (Turkish: Konstantinopolis Surları; Greek: Τείχη της Κωνσταντινούπολης) are a series of defensive stone walls that have surrounded and protected the city of Constantinople (modern Fatih district of Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built.

Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger. They saved the city, and the Byzantine Empire with it, during sieges by the Avar–Sassanian coalition, Arabs, Rus', and Bulgars, among others. The fortifications retained their usefulness even after the advent of gunpowder siege cannons, which played a part in the city's fall to Ottoman forces in 1453 but were not able to breach its walls.

Artillery consists of ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during sieges, and led to heavy, fairly immobile siege engines. As technology improved, lighter, more mobile field artillery cannons were developed for battlefield use. This development continues today; modern self-propelled artillery vehicles are highly mobile weapons of great versatility generally providing the largest share of an army's total firepower.

Originally, the word "artillery" referred to any group of soldiers primarily armed with some form of manufactured weapon or armour. Since the introduction of gunpowder and cannon, "artillery" has largely meant cannon, and in contemporary usage, usually refers to shell-firing guns, howitzers, and mortars (collectively called barrel artillery, cannon artillery or gun artillery) and rocket artillery. In common speech, the word "artillery" is often used to refer to individual devices, along with their accessories and fittings, although these assemblages are more properly called "equipment". However, there is no generally recognized generic term for a gun, howitzer, mortar, and so forth: the United States uses "artillery piece", but most English-speaking armies use "gun" and "mortar". The projectiles fired are typically either "shot" (if solid) or "shell" (if not solid). Historically, variants of solid shot including canister, chain shot and grapeshot were also used. "Shell" is a widely used generic term for a projectile, which is a component of munitions.

A fortification (also called a fort, fortress, fastness, or stronghold) is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Latin fortis ("strong") and facere ("to make").

From very early history to modern times, defensive walls have often been necessary for cities to survive in an ever-changing world of invasion and conquest. Some settlements in the Indus Valley Civilization were the first small cities to be fortified. In ancient Greece, large cyclopean stone walls fitted without mortar had been built in Mycenaean Greece, such as the ancient site of Mycenae. A Greek phrourion was a fortified collection of buildings used as a military garrison, and is the equivalent of the Roman castellum or fortress. These constructions mainly served the purpose of a watch tower, to guard certain roads, passes, and borders. Though smaller than a real fortress, they acted as a border guard rather than a real strongpoint to watch and maintain the border.

Maiden Castle is an Iron Age hillfort 1.6 mi (2.6 km) southwest of Dorchester, in the English county of Dorset. Hill forts were fortified hill-top settlements constructed across Britain during the Iron Age. The earliest archaeological evidence of human activity on the site consists of a Neolithic causewayed enclosure and bank barrow. In about 1800 BC, during the Bronze Age, the site was used for growing crops before being abandoned. Maiden Castle itself was built in about 600 BC; the early phase was a simple and unremarkable site, similar to many other hill forts in Britain and covering 6.4 ha (16 acres).

Around 450 BC it was greatly expanded and the enclosed area nearly tripled in size to 19 ha (47 acres), making it the largest hill fort in Britain and, by some definitions, the largest in Europe. At the same time, Maiden Castle's defences were made more complex with the addition of further ramparts and ditches. Around 100 BC, habitation at the hill fort went into decline and became concentrated at the eastern end of the site. It was occupied until at least the Roman period, by which time it was in the territory of the Durotriges, a Celtic tribe.

The bombard is a type of cannon or mortar which was used throughout the Late Middle Ages and the early modern period. Bombards were mainly large calibre, muzzle-loading artillery pieces used during sieges to shoot round stone projectiles at the walls of enemy fortifications, enabling troops to break in. Most bombards were made of iron and used gunpowder to launch the projectiles. There are many examples of bombards, including Mons Meg, the Basilic, the Dardanelles Gun, and the handheld bombard.

The weapon provided the name to the Royal Artillery rank of bombardier and the word bombardment.

A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or serves a decorative purpose. There are various types of walls, including border barriers between countries, brick walls, defensive walls in fortifications, and retaining walls that hold back dirt, stone, water, or noise. Walls can also be found in buildings, where they support roofs, floors, and ceilings, enclose spaces, and provide shelter and security.

The construction of walls can be categorized into framed walls and mass-walls. Framed walls transfer the load to the foundation through posts, columns, or studs and typically consist of structural elements, insulation, and finish elements. Mass-walls are made of solid materials such as masonry, concrete, adobe, or rammed earth. Walls may also house utilities like electrical wiring or plumbing and must conform to local building and fire codes.

A stockade is an enclosure of palisades and tall walls, made of logs placed side by side vertically, with the tops sharpened as a defensive wall.