Vatican – history
The word Vatican, or rather its Latin ancestor, the adjective Vaticanus, was originally applied to the ager Vaticanus (‘Vatican land’), a tract of land which extended, on the right (i.e., west) bank of the river Tiber, far beyond the territory of the modern state of Vatican City.
During the period of the Roman Republic the part of the ager Vaticanus which later became a district within the city of Rome was largely uninhabited: the Vatican Valley (i.e., the land between the Vatican Hill and the Tiber) was marshland and considered to be unhealthy. However, in the early years of the Roman Empire Agrippina the Elder (14 BCE – 33 CE) had the Vatican Valley drained and established gardens on the reclaimed land; and after her death her son, the emperor Gaius (alias Caligula, reigned 37-41 CE) commissioned the construction in these gardens of a circus, i.e., an arena for gladiatorial contests and other spectacles. The work was continued by Gaius’ successors, Claudius (reigned 41-54 CE) and Nero (reigned 54-68 CE), and stimulated further development of the area. During the reign of Nero the circus (known as the Circus of Gaius and Nero) witnessed not only gladiatorial contests and chariot races but also some of the first martyrdoms of Roman Christians, including in 67 CE the crucifixion of St. Peter, the first bishop of Rome (i.e., the first Pope), who was buried in a cemetery close to the Circus.
After the conversion to Christianity of the emperor Constantine the Great (reigned 312-337 CE), Christian worship was decriminalised in 314 by the Edict of Milan, and a few years later building began on a church, the (Old) Basilica of St. Peter, on the presumed site of Peter’s tomb. Initially the Basilica was only one among the many churches in Rome - the bishop’s (i.e., the Pope’s) residence and his administrative offices were situated on the other side of the Tiber in the Lateran Palace – but gradually it became a place of pilgrimage. It also became the church in which the popes, as the successors of St. Peter, were crowned.
The collapse of the Roman Empire at the end of the 5th century left a political vacuum in Italy, and from the 8th century onwards the Popes began to acquire secular power as the rulers of much of Central Italy – at their height the Papal States comprised the modern regions of Lazio, Marche, Umbria, Romagna, and parts of Emilia. In the 9th century the area around St. Peter’s Basilica was included within the city of Rome when, as a defence against Saracen invaders, Pope Leo IV ordered a wall to be built – it is known as the Leonine Wall - around the urban development on the west bank of the Tiber.
Towards the end of the 14th century, when the popes returned to Rome after the years of the Avignon papacy (1309-1376), the offices of the papal administration were moved to the Vatican Hill, which some years later became the site of the Pope’s official residence. Work began on a new Basilica of St. Peter at the beginning of the 16th century and continued for more than 100 years (1506-1626); and the 16th century also saw the construction, on an immediately adjacent site, of the Apostolic Palace (the Palace of Sixtus V) to house the papal administration and serve as the Pope’s official residence.
The papacy lost its secular sovereignty over parts of the Italian peninsula in the 19th century. By 1861 all the former Papal States apart from Lazio had been incorporated in the new Kingdom of Italy, and by 1870 the Vatican was reduced to a small enclave within the city of Rome. Its status as a sovereign entity – the State of Vatican City - was eventually recognised by the Lateran Treaty (1929), agreed between Pope Pius XI (reigned 1922-1939) and the Italian government, then led by Benito Mussolini (1883-1945).