• The first basilica is built at the supposed tomb of Saint Peter.
  • The Papal court is moved, leaving the area of the Vatican abandoned for over a century.
  • Pope Sixtus IV constructs the Sistine Chapel.
  • St. Peters Basilica is reconsecrated after many years of construction.
  • The Papal States are seized by Victor Emmanuel’s army during Italian unification.
  • The Italian Government and the Holy See sign three agreements altogether known as the Lateran Treaty: a treaty recognizing the independence and sovereignty of the Holy See and creating the Vatican City State; a Concordat defining the relations between the government and the church within Italy; and a financial convention providing the Holy See with compensation for its losses in 1870.
  • A revised Concordat, altering the terms of church-state relations, is signed.

Sources:

BBC News open_in_new
Britannica open_in_new