Make Roma Great Again
ru | en


Shimanovich A.A.

Castrum (Lat. Castrum, pl. castra, diminutive castellum) — is a type of military camp widespread in ancient times. It was built by Roman legionaries. Castrum was the name given to both the marching camps built at the end of each march's day, and to the long-term fortified fortresses that guarded borders of the Empire. Thanks to castra, Roman Empire was able to spread that much and maintain its power even in the most remote regions from the capital. Some castra even turned into cities, which have survived to nowadays. In the article, we are going to get a better insight on the history and structure of the castrum, an incredibly important element of legion's life as well as the whole Roman Empire's existence.

A fortified castrum's sketch

Historical note

A universal method of territory dividing for camps, most likely appeared during the Punic Wars (III century BC). At the time, castra were build along the borders and state (consular or praetor) roads, with one march day. Structurally these camps resembled cities.

According to the Jewish historian and military commander Josephus (37-100 CE), first century CE, legionaries set up a camp at the end of each day. That allowed to calculate campaign's duration in days based on the number of camps. Before 69 CE, permanent border castra, like marching camps were built from turf and wood. Only in 69 CE, when the Flavians came to power, legions started building long-term fortresses from stone or brick.

By the IV-V centuries CE, castra seem to loose their purpose, mostly because of a significant decline in military power and abundance of old military traditions. Soviet historian V. D. Ivanov wrote about that: "Old Roman infantry did not go to bed until they dug a ditch around the camp, until banket was covered with sharp stakes, until the camp-fortress was shut by three gates. Later, having got used to play emperors, the soldier's didn't burden themselves anymore with drudgery daily work... and during campaigns, soldiers could only be forced to dig in in the face of imminent danger..."

Setting up a camp

The construction of a marching camp had an established order. Usually, at the end of a day, a small group would go ahead of the Legion to find the most suitable and protected location. There were strict requirements for the camp location: it should be well protected on all sides, convenient for defense and preferably have a water source. After the place has been chosen, the first step was to mark the location of the commander's tent, and the "pretoria" surrounding the tent (Lat. praetorium) - a square or rectangular area on where all senior officers' tents were placed. And from that position went two roads' directions (cardo and decumanus). These roads crossed the camp cross-like, and from them the rest of the camp was designed.

When the legion approached the designated area, the soldiers immediately began to erect fortifications. Works were often performed in full gear, wearing armor and weapons. First of all they built fortifications: a moat was dug around and a solid rampart was erected, reinforced with turf or stones, and in case of long-term fortification, it was also reinforced with wattles. The rampart was necessarily reinforced with sharpened stakes. It should be noted, that in general the entire Roman fortification system was performed according to the system: fossa – agger – vallum (moat – embankment – shaft), more than that there could've been more than one moat.

A reconstruction of Castrum's defens structures

After fortification construction, legionaries set up tents. Firstly, they set up commander's tent and senior officers' tents: they were set up around the perimeter of the praetorium. Last of all were set up soldiers' tents. It was necessary to maintain a certain distance between tents and fortification's perimeter to allow troops conveniently maneuver in the camp and to protect tents from arrow fire, which can fly over the fortification. Usually, legionaries had from 2 to 5 hours to set up the fortifications, depending on the terrain and tactical situation, after that legionaries settled down for the night.

Greek historian Polybius (200-120 BCE) gave a description of an average marching castrum. He wrote that the Roman military camp was formed as "equilateral quadrilateral", or square, and the present streets made it similar to the city: "The Tents are two hundred feet away from the rampart. All available space provides great and varied amenities. Thus, it is very convenient for entering and leaving the camp, because these are separate units, each with its own street, which goes to this free space, soldiers don't get into each others way. "It should be noticed, that most of the found castra's remains weren't equilateral square shaped, which indicates that rectangular form prevailed. There was also a theoretical guideline on the aspect ratio of the camp, according to which the ratio of its length and width should be 3/2. It was written in the treatise " On the organization of military camps "(Lat. De munitionidus castrorum) under the authorship of a certain Pseudo-Gigin (a pseudonym attributed to several ancient authors at the same time. Who exactly was hiding under it has not yet been precisely established).

Big castrum's scheme
Castrum's sketch

Different sources give different castrum's size. The average typical size of the camp was approximately 450-500 meters wide and 550-650 meters long. There were gates on each of the four sides of the camp, connected by two main roads. As usual, if the camp was set up close to the enemy, one gate was necessarily turned to the enemy's side (such gates were called porta praetoria), and behind the opposite gate (porta decumana) can be sometimes stationed merchants following the legion. The gates were always designed to be wide enough so there were no obstacles when exiting the camp. The center of the camp was the praetorium, which, as already mentioned, was the place where commander's tent and senior officer's tents stood. Often, there also was a sacrificial altar. In addition to that, the praetorium had a divination place, Quaestor's tent — treasurer's, as well as the tribunal - a mound where from commander could address to the legionaries. Auxiliary troops were stationed behind the praetorium, while the rest and the most part of the camp stationed legionaries' tents and cavalry on both sides of the main street "via praetoria".

Camp removal

The camp removal also had a special order. With the first trumpet signal, the tents were removed, with the second one all the tents and other stuff was loaded on pack animals. Josephus wrote: "At the same time, they burn the fortifications so enemy can't use them, being confident that in case of they need fortifications they can build another one with ease. Third trumpet means march time — legionaries line up and tarring soldiers hurry to get in line. Then the messenger, standing on right hand from the commander asks three times in native language: is everything prepared for battle? The soldiers shout out loudly and joyfully as much as asked times: "Yes, everything is done!". Quite often before the messenger finished, legionaries full of battle enthusiasm with hands raised shout out only one war cry". "Then they set out and move in silence, in battle line order."

Legionnaires of the Tenth Legion exit the Castrum
A Fragment of a Roman military camp, reconstruction

Kastra - cities

Long-term castra were built in the most important supply-locations. They were reinforced with wooden, and later with stone walls. Instead of tents there were stone barracks and buildings of the military administrative apparatus as well as public institution buildings. Their planning scheme remained almost identical to temporary castra. The area inside the walls was called city "urbs", and the land outside the walls was called "pomerium". Legionnaires and their families usually settled here. Such a castrum included a principium (headquarters), a praetorium, barracks, food warehouses, training rooms, workshops, first cohort soldiers' barracks, stables and a hospital.

Over time these camps connected by roads with the metropolis, became centers attracting commerce and crafts. They overgrew with residential buildings: with family soldier's houses, craftsmen houses, trader houses. Roman commanders of the end of republic era and emperors created such settlements, by disbanding armies as wars ended. As a reward for their service, soldiers (veterans and reservists) received money and land for farming. They settled there quite densely. Usually, the population of such towns consisted from the veterans of the same military unit. Cities that grew out of Roman castra include: Turin, Florence, Lucca, Timgad, London, Vienna, Bonn, Trier, Algiers, Budapest, Belgrade, and others.

A sektch of a long-term castrum's structure

"Urbs Quadrata" or Square city

Wherever the Roman legionnaires performed emperor's will, they always brought Rome with them: Roman civilization, Roman laws, Roman culture. That's why, every fort-camp, especially long-term one, built even in the most remote province, somehow carried a bit of distant Rome culture in it. Square camp shape in particular also contributed to it.

Rome was often called "Urbs Quadrata" (translation from Latin square city), implying the principle of sacred monuments' foundation that became the basis of an equally sacred city. Those principals are unclear to modern people. All the constructed building were part of an order, or a Whole (as Marcus Aurelius called the world order). In simple terms, buildings erected by man in accordance with a sacred ritual were at same level as entities created by Gods. Thus, the circle represented the divine reality, and the square in its turn represented the earth one. That's why the holy city of Rome was associated not only with earth being, but as well with a divine being.

The Castra embodied the Roman Empire order, which was brought to Roman province. Also castra represented both of these principles, telling poorly educated, conquered peoples about the immeasurably great Roman foundation it was based on.

Weissenburg's Castrum (Birciana)

It's one of the most famous castra. Its remains have survived to nowadays. It was presumably built in 90 CE to protect freshly aquired territories on the north from Danube under the emperor Domitian. Originally it was constructed from wood, it was later rebuilt with stone in the middle of the second century CE.

It is known that the First Spanish Aurian Ala (Ala I Hispanorum Auriana) (an auxiliary unit of the Roman army) was stationed in the Weissenburg Castrum during the first and third centuries CE. In addition to that, there is a suggestion that the IX auxiliary Batavoran Cohort (Cohors IX Batavorum) was temporarily stationed in this camp at the beginning of the second century CE.

A reconstruction of Weissenburg camp's main gate

Currently the Weissenburg Castrum's ruins are under German government protection and are included in the UNESCO list as a cultural heritage site. The camp was first discovered by German archaeologists in 1890, the excavations were completed by 1905, and since then, restoration work has been gradually carried out in the thermal baths.

At the moment the Castrum-Museum hasa reconstructed stone gates (porta decumana), which were completely recreated in 1990. It also has the remains of a large thermal bath complex and the foundation of the principatia building.

Heated dressing room with hypocast (heating system)
Square reservoir in the caldarium (main room of the thermal baths with hot water)
Cold water pool with the original, preserved floor

Tenth Legion's Castrum at Masada

In 66 CE, during a revolt the Masada fortress was captured by the Zealots, Jewish rebels who advocated for eradication of Hellenistic and Latin cultures from the Jewish lands, and who wanted to overthrow Roman regime. According to Josephus, during the assault the Zealots completely massacred whole Roman garrison. In 67 CE, in fortress appeared the Sicarii (the"fighting wing" of the Zealots, who used the path of direct attacks on Romans to fight them), who are mostly the reason First Jewish War began. After the Jerusalem was captured in 70 CE, the Roman army payed its attention to Masada, which turned out to be the last stronghold of recalcitrant radicals. The task to capture the fortress was to be performed by the Legio X Fretensis under the leadership of the Roman politician and commander Lucius Flavius Silva. There were less than a thousand people in the fortress, but due to their tenacity and favorable castle position, protected by steep cliffs, the siege lasted for the whole three years. The Tenth Legion built a siege rampart at the foot of the fortress, a banket which allowed to come directly to the walls. It preserved to nowadays and is used as a tourist route. And ruins of castrum himself still keep tenth legion legionaries' achievements.

A modern view of the Masada Fortress
A modern view of the Castrum's ruins

The siege ended tragically: in 73 CE, following the call of the head of the Sicarii, Elazar ben-Yair, the besieged committed suicide en masse on the first day of the Jewish holiday of Passover. Describing these events, Josephus refers to the story of two women who together with several children took refuge in a cave and told the Romans who entered the fortress about how the men killed their wives and children, and then each other. "I'm sure Romans will be disappointed if they don't take us alive, there wouldn't be anything to prey on, their expectations would be shattered. We won't touch only our food supplies, so they would understand that we did not suffer from hunger or lack of water, but we ourselves chose death over slavery — as we had previously decided......So they all perished with the certainty that they had not left behind a single soul to be abused by the Romans. The next day the Romans went up to Masada, and when they found the dead heaps, they did not rejoice at the sight of the fallen enemies, but only stood in silence, struck by the greatness of their spirit and the unshakable contempt for death" - Josephus.


Josephus. "The Jewish War" / translated by Ya. L. Chertka in 1900, with an introduction and translator's note. Vekhi Library, 2004.

Livy Titus. Istoriya Rima ot osnovaniya goroda [History of Rome from the foundation of the city]. edited by M. L. Gasparov and G. S. Knabe, vol. I-III. Moscow, 2002

Polybius. Universal History, vol. I (books I-V), Moscow, 1890.

Polyakov Evgeny Nikolaevich, Mayorova E. V., Shapovalova E. E. Features of a regular planning grid in the military architecture of ancient Rome // Bulletin of TSASU. 2009.

Maklyuk A.V. Army of the Roman Empire. Ocherki traditsii i mentalnosti [Essays on Traditions and Mentality], N. Novgorod, 2000

Dion Cassius. Dio’s Roman History: In Nine Volumes / With an English Translation by E. Cary, on the Basis of the Version of H. B. Foster. London; New York, 1914-1927


A banket built by legionnaires to get to the walls of the Masada Fortress
A view on the ruins of Tenth Legion's castrum from the remains of the fortress
Principia's foundation (headquarters)