A citadel is a fortress for protecting a town, sometimes incorporating a castle. Fortifications are Military Constructions and Buildings designed for defense in Warfare Humans have constructed defensive works for A town is a type of settlement ranging from a few to several thousand (occasionally hundreds of thousands inhabitants although it may be applied loosely even to huge metropolitan A castle is a defensive structure seen as one of the main symbols of the Middle Ages.  The term derives from the same Latin root as the word "city", civis, meaning citizen. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome.
Citadels are most often used to protect a garrison or political power from the inhabitants of the town it is defending. They were designed to ensure loyalty from the town which they defended.
For example Barcelona had a great citadel built in 1714 to intimidate the Catalans against repeating their mid 17th and early 18th century rebellions against the Spanish central government. Barcelona ( Catalan bəɾsəˈlonə Spanish baɾθeˈlona is the capital and most populous city of the Autonomous Community of Catalonia The Catalans are the people from Catalonia, an Autonomous community of Spain, including people originating in that region but living elsewhere In the 19th century, as soon as the political climate had liberalised enough to permit it, the people of Barcelona had the citadel torn down, and replaced it with the city's main central park, the Parc de la Ciutadella. A similar example is the Citadella in Budapest, Hungary. Citadella is the Hungarian word for Citadel, a kind of fortress. Budapest ( also /ˈbʊ-/) is the capital city of Hungary. As the largest city of Hungary it serves as the country's principal Political, Hungary (Magyarország 'mɔɟɔrorsaːg) officially in English the Republic of Hungary ( Magyar Köztársaság, literally Magyar (Hungarian Republic The Citadelle of Quebec still survives, as the largest citadel still in official military operation in North America, after more than two hundred years of existence. The Citadelle —the French name is used both in English and French—is a military installation and official residence located atop Cap Diamant, adjoining the Plains of
In ancient Greece, the citadel, placed on a commanding eminence, was important in the life of the people, serving as a refuge and stronghold in peril and containing military and food supplies, the shrine of the god and a royal palace. Greece (Ελλάδα transliterated: Elláda, historically, Ellás,) officially the Hellenic Republic (Ελληνική Δημοκρατία A stronghold is a strongly fortified defensive structureThe history of fortified buildings extends from antiquity to modern times A shrine, from the Latin scrinium (‘box’ also used as a desk like the French bureau) was originally a container usually made of precious materials used A palace is a grand residence especially the home of a Head of state or some other high-ranking Public figure. In the Middle Ages the citadel was the last defense of a besieged army, often held after the town had been conquered, and affording retreat to the people living in the areas around the town.
In a fortification with bastions, the citadel is the strongest part of the system, sometimes well inside the outer walls and bastions, but often forming part of the outer wall for the sake of economy. Fortifications are Military Constructions and Buildings designed for defense in Warfare Humans have constructed defensive works for A bastion is a structure projecting outward from the main enclosure of a Fortification, situated in both corners of a straight wall (termed curtain with the shape It is positioned to be the last line of defense should the enemy breach the other components of the fortification system.