Fortifications are military constructions designed for defensive warfare. They have been used for many thousands of years, in a variety of increasingly complex designs. The practice of improving an area's defense is also known as "fortification". Many military installations are known as forts, although they are not always "fortified".

The art of laying out a military camp or constructing a fortification has often been called castrametation, since the time of the Roman legions. The art of laying a siege to a fortification and destroying it was usually called poliorcetics. In some texts this term is also applied to the art of building a fortification.

List of fortifications
List of forts

See also

• Abatis
• Barbed wire
• Bastle house
• Blockhouse
• Bunker
• Castle
• City wall
• Great Wall of China
• Maginot Line
• Martello tower
• Medieval fortification
• Military history
• Military engineer
• Medieval warfare
• Peel tower
• Pillbox
• Razor wire
• Sandbag
• Siege engine
• Siege
• Stockade
• Turret
• Vauban
• Wire entanglement
• Wire obstacle

---

• Fortress (chess) is also a chess engine.