The Vatican’s history as the seat of the Catholic Church began with the construction of a basilica over St. Peter’s grave in Rome in the 4th century A.D. The area developed into a popular pilgrimage site and commercial district, although it was abandoned following the move of the papal court to France in 1309. After the Church returned in 1377, famous landmarks such the Apostolic Palace, the Sistine Chapel and the new St. Peter’s Basilica were erected within the city limits. Vatican City was established in its current form as a sovereign nation with the signing of the Lateran Pacts in 1929.

The area off the west bank of the Tiber River that comprises the Vatican was once a marshy region known as Ager Vaticanus. During the early years of the Roman Empire, it became an administrative region populated by expensive villas, as well as a circus built in the gardens of Emperor Caligula’s mother. After much of Rome was leveled in a fire in A.D. 64, Emperor Nero executed St. Peter and other Christian scapegoats at the base of Vatican Hill, where they were buried in a necropolis.

Having embraced Christianity with the Edict of Milan in 313, Emperor Constantine I began constructing a basilica over St. Peter’s tomb in 324. St. Peter’s Basilica became a spiritual center for Christian pilgrims, leading to the development of housing for clergymen and the formation of a marketplace that became the thriving commercial district of Borgo.

Following an attack by Saracen pirates that damaged St. Peter’s in 846, Pope Leo IV ordered the construction of a wall to protect the holy basilica and its associated precincts. Completed in 852, the 39-foot-tall wall enclosed what was inaugurated Leonine City, an area covering the current Vatican territory and the Borgo district. The walls were continually expanded and modified until the reign of Pope Urban VIII in the 1640s.

Although the pontiff traditionally lived at the nearby Lateran Palace, Pope Symmachus built a residence adjacent to St. Peter’s in the early 6th century. It was expanded hundreds of years later by both Eugene III and Innocent III, and in 1277 a half-mile-long covered passageway was assembled to link the structure to Castel Sant’Angelo. However, the buildings were all abandoned with the shift of the papal court to Avignon, France, in 1309, and over the next half-century the city fell into disrepair.

Following the return of the Catholic Church in 1377, the clergy sought to restore the walled city’s luster.

Nicholas V circa 1450 commenced construction of the Apostolic Palace, eventually the permanent home of his successors, and his collection of books became the foundation of the Vatican Library. In the 1470s, Sixtus IV began work on the famed Sistine Chapel, featuring frescoes created by such leading Renaissance artists as Botticelli and Perugino.

Significant changes to the city took place after Julius II became pope in 1503. Julius commissioned Michelangelo to paint the Sistine Chapel ceiling in 1508, and tapped architect Donato Bramante design the Belvedere Courtyard. The pontiff also elected to tear down the 1,200-year-old St. Peter’s Basilica and have Bramante build a new one in its place.

The death of Julius in 1513 and Bramante the following year led to a decades-long dispute over how to continue the project, until Michelangelo ended the deadlock in 1547 with his choice to follow Bramante’s original design. Giacomo della Porta completed St. Peter’s celebrated dome in 1590, and work on the grand structure finally finished in 1626. Measuring 452 feet tall and encompassing 5.7 acres, the new St. Peter’s stood as the world’s biggest church until the completion of the Ivory Coast’s Basilica of Our Lady of Peace of Yamoussoukro in 1989.

The Vatican Museums originated from the sculpture collection of Julius II, its earliest gallery opened to the public by Pope Clement XIV in 1773 and expanded by Pope Pius VI. Subsequent popes continued to bolster the renowned collections over the years, with the Gregorian Egyptian Museum, the Ethnological Museum and the Collection of Modern and Contemporary Religious Art among the additions.

Popes traditionally held power over regional territories known as the Papal States until 1870, when the unified Italian government claimed virtually all of the land outside of the city walls. A standoff between the church and secular government ensued for the next 60 years, until an agreement reached with the Lateran Pacts in February 1929. Signed by Benito Mussolini on behalf of King Victor Emmanuel III, the pacts established Vatican City as a sovereign entity distinct from the Holy See, and granted the church $92 million as compensation for the loss of the Papal States.

The Vatican remains the home of the pope and the Roman Curia, and the spiritual center for some 1.2 billion followers of the Catholic Church. The world’s smallest independent nation-state, it covers 109 acres within a 2-mile border, and possesses another 160 acres of holdings in remote locations. Along with the centuries-old buildings and gardens, the Vatican maintains its own banking and telephone systems, post office, pharmacy, newspaper, and radio and television stations. Its 600 citizens include the members of the Swiss Guard, a security detail charged with protecting the pope since 1506.