The History of the Catholic Church from apostolic times covers a period of nearly 2,000 years,  making it the world's oldest and largest institution. It dates its beginning to the confession of Peter, and the establishment of the Church by Jesus Christ. Catholic doctrine states that Christ is the head of his Mystical Body, the Catholic Church. The history of the Roman Catholic Church is integral to the History of Christianity and the history of Western civilization.
Roman Catholic Church history is based on the interpretation of Matthew 16:18 as delineating Christ's designation of Apostle Peter and his successors in Rome to be secular head of his Church. The authority of the Apostle Peter and his successors is thus viewed as a continuous history from Jesus Christ through the ecumenical councils, a view shared by many historians as well. The institution of the papacy as it exists today developed through the centuries. Church tradition records that Peter became the first leader of Christians in the Imperial capital of Rome. The apostles and many Christians traveled to northern Africa, Asia Minor, Arabia, Greece, and Rome to found the first Christian communities. Christianity spread quickly through the Roman Empire, and by the second century there were many established bishoprics within the Empire including Northern Africa, France, Italy, Syria, and Asia Minor, and twenty bishoprics outside the empire, mainly in Armenia.  Irenaeus (d. 202) defended the apostolic tradition, which can only be safeguarded with the central primacy of Rome.[
In 313, the struggles of the early Church were lessened by the legalisation of Christianity by the Emperor Constantine I. In 383, Christianity became the official religion of the Roman Empire by the decree of the Emperor, which would persist until the fall of the Western Empire, and later, with the Eastern Roman Empire, until the capture of Constantinople. At this time there were considered five primary sees according to Eusebius: Rome, Constantinople, Antioch, Jerusalem and Alexandria.
After the destruction of the western Roman Empire, the church in the West preserved classical civilization, establishing monasteries, and sending missionaries to convert the pagan peoples of northern Europe, as far as Ireland in the north. In the East, the Byzantine Empire preserved Catholicism, up until the massive invasions of Islam in the mid-seventh century. The invasions of Islam devastated three of the five sees, capturing Jerusalem first, then Alexandria, and then finally in the mid-eighth century, they captured Antioch.
The whole period of the next five centuries was dominated by the struggle between the Catholic Church and Islam throughout the Mediterranean. The battles of Poitiers, and Toulouse preserved the west, even as Rome itself was ravaged in 850, and Constantinople besieged.
In the 11th century, as the invasions of Islam strained relations between the primarily Greek church in the East, and the Latin church in the West, it split apart, partially due to the split over papal power, the fourth crusade, and the sacking of Constantinople by the Europeans proved the final breach.
In the 16th century, in response to the Protestant Reformation, the Church engaged in a process of substantial reform and renewal, known as the Counter-Reformation. In subsequent centuries, Catholicism spread widely across the world, though seeing a reduction in its hold on European countries from the growth of religious scepticism after the Enlightenment. The Second Vatican Council in the 1960s introduced the most significant changes to Catholic practices since the Council of Trent three centuries before.