Palisade in the context of "Stockade"

A defensive wall is a fortification 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 such as curtain walls with towers, bastions and gates for access to the city. From ancient to modern times, they were used to enclose settlements. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China, Walls of Benin, Hadrian's Wall, Anastasian Wall, and the Atlantic Wall, which extended far beyond the borders of a city and were used to enclose regions or mark territorial boundaries. In mountainous terrain, defensive walls such as letzis were used in combination with castles to seal valleys from potential attack. Beyond their defensive utility, many walls also had important symbolic functions – representing the status and independence of the communities they embraced.

Existing ancient walls are almost always masonry structures, although brick and timber-built variants are also known. Depending on the topography 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.

The Antonine Wall (Latin: Vallum Antonini) was a turf fortification on stone foundations, built by the Romans across what is now the Central Belt of Scotland, between the Firth of Clyde and the Firth of Forth. Built some twenty years after Hadrian's Wall to the south, and intended to supersede it, while it was garrisoned it was the northernmost frontier barrier of the Roman Empire. It spanned approximately 63 kilometres (39 miles) and was about 3 metres (10 feet) high and 5 metres (16 feet) wide. Lidar scans have been carried out to establish the length of the wall and the Roman distance units used. Security was bolstered by a deep ditch on the northern side. It is thought that there was a wooden palisade on top of the turf. The barrier was the second of two "great walls" created by the Romans in Great Britain in the second century AD. Its ruins are less evident than those of the better-known and longer Hadrian's Wall to the south, primarily because the turf and wood wall has largely weathered away, unlike its stone-built southern predecessor.

Construction began in AD 142 at the order of Roman Emperor Antoninus Pius. Estimates of how long it took to complete vary widely, with six and twelve years most commonly proposed. Antoninus Pius never visited Britain, unlike his predecessor Hadrian. Pressure from the Caledonians probably led Antoninus to send the empire's troops farther north. The Antonine Wall was protected by 16 forts with small fortlets between them; troop movement was facilitated by a road linking all the sites known as the Military Way. The soldiers who built the wall commemorated the construction and their struggles with the Caledonians with decorative slabs, twenty of which survive. The wall was abandoned only eight years after completion, and the garrisons relocated rearward to Hadrian's Wall. Most of the wall and its associated fortifications have been destroyed over time, but some remains are visible. Many of these have come under the care of Historic Environment Scotland and the UNESCO World Heritage Committee.

Ringforts or ring forts are small circular fortified settlements built during the Bronze Age, Iron Age and early Middle Ages up to about the year 1000 AD. They are found in Northern Europe, especially in Ireland. There are also many in South Wales and in Cornwall, where they are called rounds. Ringforts come in many sizes and may be made of stone or earth. Earthen ringforts would have been marked by a circular rampart (a bank and ditch), often with a stakewall. Both stone and earthen ringforts would generally have had at least one building inside.

The word pā (Māori pronunciation: [ˈpaː]; often spelled pa in English) can refer to any Māori village or defensive settlement, but often refers to hillforts – fortified settlements with palisades and defensive terraces – and also to fortified villages. Pā sites occur mainly in the North Island of New Zealand, north of Lake Taupō. Over 5,000 sites have been located, photographed and examined, although few have been subject to detailed analysis. Variations similar to pā occur throughout central Polynesia, in the islands of Fiji, Tonga and the Marquesas Islands.

In Māori culture, a great pā represented the mana (prestige or power) and strategic ability of an iwi (tribe or tribal confederacy), as personified by a rangatira (chieftain). Māori built pā in various defensible locations around the territory (rohe) of an iwi to protect fertile plantation-sites and food supplies.