Monte Cassino (today usually spelled Montecassino) is a rocky hill about 130 kilometres (80 mi) southeast of Rome, in the Latin Valley, Italy, 2 kilometres (1+1⁄4 mi) west of Cassino and at an elevation of 520 m (1,710 ft). Site of the Roman town of Casinum, it is best known for its abbey, the first house of the Benedictine Order, having been established by Benedict of Nursia himself around 529. It was for the community of Monte Cassino that the Rule of Saint Benedict was composed.
The first monastery on Monte Cassino was sacked by the invading Lombards around 570 and abandoned. Of the first monastery almost nothing is known. The second monastery was established by Petronax of Brescia around 718, at the suggestion of Pope Gregory II and with the support of the Lombard Duke Romuald II of Benevento. It was directly subject to the pope and many monasteries in Italy were under its authority. In 883 the monastery was sacked by Saracens and abandoned again. The community of monks resided first at Teano and then from 914 at Capua before the monastery was rebuilt in 949. During the period of exile, the Cluniac Reforms were introduced into the community.
The 11th and 12th centuries were the abbey's golden age. 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. It maintained good relations with the Eastern Church, even receiving patronage from Byzantine emperors. It encouraged fine art and craftsmanship by employing Byzantine and even Saracen artisans. In 1057, Pope Victor II recognised the abbot of Monte Cassino as having precedence over all other abbots. 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 the monastery's chronicle was written by two of its own, Cardinal Leo of Ostia and Peter the Deacon (who also compiled the cartulary).
By the 13th century, the monastery's decline had set in. In 1239, the Emperor Frederick II garrisoned troops in it during his war with the Papacy. In 1322, Pope John XXII elevated the abbey into a bishopric but this was suppressed in 1367. The buildings were destroyed by an earthquake in 1349, and in 1369 Pope Urban V demanded a contribution from all Benedictine monasteries to fund the rebuilding. In 1454 the abbey was placed in commendam and in 1504 was made subject to the Abbey of Santa Giustina in Padua.
In 1799, Monte Cassino was sacked again by French troops during the French Revolutionary Wars. The abbey was dissolved by the Italian government in 1866. The building became a national monument with the monks as custodians of its treasures. In 1944 during World War II it was the site of the Battle of Monte Cassino and the building was destroyed by Allied bombing. It was rebuilt after the war.
After the reforms of the Second Vatican Council the monastery was one of the few remaining territorial abbeys within the Catholic Church. On 23 October 2014, Pope Francis applied the norms of the motu proprio Ecclesia Catholica of Paul VI (1976) to the abbey, removing from its jurisdiction all 53 parishes and reducing its spiritual jurisdiction to the abbey itself – while retaining its status as a territorial abbey. The former territory of the Abbey, except the land on which the abbey church and monastery sit, was transferred to the diocese of Sora-Cassino-Aquino-Pontecorvo. Pope Francis at the same time appointed Father Donato Ogliari as the new Abbot who will serve as the 192nd successor of Saint Benedict. As of 2015, the monastic community consists of thirteen monks.