Engineering barrages

thumb|Castillo San Felipe del Morro, Puerto Rico. The fortress and walled city of [[Old San Juan are a UNESCO World Heritage Site.]]

thumb|A wooden fence thumb|During the Cold War, West German trains ran through [[East Germany. This 1977 view shows how East German authorities placed fences near the tracks to keep potential defectors at bay]]

type of steel fencing wire constructed with sharp edges or points arranged at intervals along the strand(s)

thumb|Moat at Beaumaris Castle, [[Wales]] A moat is a deep, broad ditch dug around a castle, fortification, building, or town, historically to provide it with a preliminary line of defence. Moats can be dry or filled with water. In some places, moats evolved into more extensive water defences, including natural or artificial lakes, dams and sluices. In older fortifications, such as hillforts, they are usually referred to simply as ditches, although the function is similar. In later periods, moats or water defences may be largely ornamental. They could also act as a sewer.

thumb|In this seventeenth-century plan of the fortified city of Casale Monferrato the citadel is the large star-shaped structure on the left.

thumb|right|Drawing of a bastion

A boulevard is a type of broad avenue planted with rows of trees, or in parts of North America, any urban highway or wide road in a commercial district.

thumb|right|Reconstruction of a palisade in a Celtic village at St Fagans National History Museum, [[Wales]] thumb|right|Reconstruction of a medieval palisade in Germany

concrete anti-tank obstacles

thumb|Roman caltrop at the Westphalian Museum of Archeology (German: Westfälisches Museum für Archäologie), Herne, North Rhine-Westphalia, Germany

static anti-tank obstacle defense

large balloon tethered with metal cables

medieval defensive obstacle

thumb|right|Abatisses are used in war to keep the approaching enemy under fire for as long as possible. An abatis, abattis, or abbattis is a field fortification consisting of an obstacle formed of the branches of trees laid in a row, with the sharpened tops directed outwards, towards the enemy. The trees are usually interlaced or tied with wire. Abatis are used alone or in combination with wire entanglements and other obstacles.

length of bank or wall forming part of the defensive boundary of a fortification

thumb|Embankment dam with two berms

metal strips with sharp edges whose purpose is to prevent passage by humans

gabion primarily used for flood control and military fortifications

type of barbed wire or razor wire, formed in large coils

device or weapon used to impede or stop the movement of wheeled vehicles by puncturing their tires

thumb|300x300px|Novgorod Detinets in Veliky Novgorod, Russia

temporary floating barrier used to contain an oil spill

decorative fence often designating domestic property lines

Naviglio of Milan

thumb|A German concrete pillbox or blockhouse after capture by the Coldstream Guards on the outskirts of Houlthulst Forest, Battle of Poelcappelle, 10 October 1917

type of military fortification

military term for a wide range of structures, devices or measures for constraining or impeding the movement of troops and forces