Site of the Roman town of Casinum, it is widely known for its abbey, the first house of the Benedictine Order, having been established by Benedict of Nursia himself around 529.

It acquired a large secular territory around Monte Cassino, the so-called Terra Sancti Benedicti ("Land of Saint Benedict"), which it heavily fortified with castles.

Many monks rose to become bishops and cardinals, and three popes were drawn from the abbey: Stephen IX (1057–58), Victor III (1086–87) and Gelasius II (1118–19).

During this period, a monastic chronicle, Chronica sacri monasterii casinensis [it], was written by two of its own, Cardinal Leo of Ostia and Peter the Deacon (who also compiled the cartulary).

The biography records that the area was still largely pagan at the time; Benedict's first act was to smash the sculpture of Apollo and destroy the altar.

Pope Gregory I's account of Benedict's seizure of Monte Cassino: Now the citadel called Casinum is located on the side of a high mountain.

Pope Gregory also relays that the monks found a pagan idol of bronze when digging at the site (which when thrown into the kitchen gave the illusion of a fire until dispelled by Benedict).

"[11] Scholars note that this striking contrast is not stressed by Gregory but rather both settings are portrayed as part of a single battle account against the same demonic enemy.

Unlike the stories that may have influenced Pope Gregory's structure of the biography, Benedict's victories are practical, preventing Satan from stopping work on the abbey at Monte Cassino.

"[11] After the completion of the abbey, Satan's appearances in the story diminish back to the same level as Subiaco, "Only after the saint's death and by God's permission would other enemies, the Lombards, succeed in sacking it.

He wrote the Benedictine Rule that became the founding principle for Western monasticism, received a visit from Totila, king of the Ostrogoths (perhaps in 543, the only remotely secure historical date for Benedict), and died there.

Benedict founded twelve communities for monks at nearby Subiaco (about 64 km to the east of Rome), where hospitals were settled, too, as adjuncts to the monasteries to provide charity.

Adalbert de Vogüé recounts that "Traces have been found of the oratories of St. Martin and of St. John the Baptist, with additions from the eighth and eleventh centuries, together with their pre-Christian cellars.

In 744, a donation of Gisulf II of Benevento created the Terra Sancti Benedicti, the secular lands of the abbacy, which were subject to the abbot and nobody else save the pope.

Thus, the monastery became the capital of a state comprising a compact and strategic region between the Lombard principality of Benevento and the Byzantine city-states of the coast (Naples, Gaeta, and Amalfi).

Among the great historians who worked at the monastery, in this period there is Erchempert, whose Historia Langobardorum Beneventanorum is a fundamental chronicle of the ninth-century Mezzogiorno.

So they began to buy and collect medical and other books by Greek, Roman, Islamic, Egyptian, European, Jewish, and Oriental authors.

Monks reading and copying the medical texts learned a lot about human anatomy and methods of treatment, and then put their theoretic skills into practice at monastery hospital.

By the 10–11th centuries Monte Cassino became the most famous cultural, educational, and medical center of Europe with a great library in Medicine and other sciences.

That is why the first High Medical School in the world was soon opened in nearby Salerno which is considered today to have been the earliest Institution of Higher Education in Western Europe.

So, Montecassino and Benedictines played a great role in the progress of medicine and science in the Middle Ages, and with his life and work St. Benedict himself exercised a fundamental influence on the development of European civilization and culture and helped Europe to emerge from the "dark night of history" that followed the fall of the Roman empire.

The buildings of the monastery were reconstructed in the 11th century on a scale of great magnificence, artists being brought from Amalfi, Lombardy, and even Constantinople to supervise the various works.

A detailed account of the abbey at this date exists in the Chronica monasterii Cassinensis by Leo of Ostia and Amatus of Monte Cassino gives us our best source on the early Normans in the south.

Abbot Desiderius sent envoys to Constantinople some time after 1066 to hire expert Byzantine mosaicists for the decoration of the rebuilt abbey church.

In 1321, Pope John XXII made the church of Monte Cassino a cathedral, and the carefully preserved independence of the monastery from episcopal interference was at an end.

The abbey itself however, was not initially utilised by the German troops as part of their fortifications, owing to General Kesselring's regard for the historical monument.

The Gustav Line stretched from the Tyrrhenian to the Adriatic coast in the east, with Monte Cassino itself overlooking Highway 6 and blocking the path to Rome.

General Sir Harold Alexander, with the support of numerous Allied commanders, ordered the bombing, which was conducted due to several reports from British Indian Army officers suggesting that German forces were occupying the monastery; the abbey was considered a key observation post by all those who were fighting in the field.

[24] Another account, however, from revisionist author Franz Kurowski's The History of the Fallschirmpanzerkorps Hermann Göring: Soldiers of the Reichsmarschall, notes that 120 trucks were loaded with monastic assets and art which had been stored there for safekeeping.

The trucks were loaded and left in October 1943, and only "strenuous" protests resulted in their delivery to the Vatican, minus the 15 cases which contained the property of the Capodimonte Museum in Naples.