The name "Vatican"
is ancient and predates Christianity, coming
from the Latin Mons Vaticanus, Vatican
Hill. The territory of Vatican City is part of
the Mons Vaticanus, and of the adjacent
former Vatican Fields where St. Peter's
Basilica, the Apostolic Palace, the Sistine
Chapel, and museums were built, along with
various other buildings. The area was part of
the Roman rione of Borgo until 1929. Being
separated from the city, on the west bank of the
Tiber river, the area was an outcrop of the city
that was protected by being included within the
walls of Leo IV, and later expanded by the
current fortification walls of Paul III/Pius IV/Urban
VIII. When the Lateran Treaty of 1929 that gave
the state its present form was being prepared,
the boundaries of the proposed territory was
influenced by the fact that much of it was all
but enclosed by this loop. For some tracts of
the frontier, there was no wall, but the line of
certain buildings supplied part of the boundary,
and for a small part of the frontier a modern
wall was constructed. The territory included St.
Peter's Square, which was not possible to
isolate from the rest of Rome, and therefore a
largely imaginary border with Italy runs along
the outer limit of the square where it touches
on Piazza Pio XII and Via Paolo VI. St. Peter's
Square is reached through the Via della
Conciliazione which runs from the Tiber River to
St. Peter's. This grand approach was constructed
by Mussolini after the conclusion of the Lateran
Treaty.
According to the Lateran Treaty, certain properties of the Holy See that are located in Italian territory, most notably Castel Gandolfo and the Patriarchal Basilicas, enjoy extraterritorial status similar to that of foreign embassies. These properties, scattered all over Rome and Italy, house essential offices and institutions necessary to the character and mission of the Holy See. Castel Gandolfo and the named basilicas are patrolled internally by police agents of the Vatican City State and not by Italian police. St. Peter's Square is ordinarily policed jointly by both.
