On February 11, 1929, the Lateran Treaty was signed. (Actually, the Treaty was ratified in June of that year—so I guess the date to pop open the chianti would be June 7.)
Anyway, in case you’ve forgotten your European history, the Lateran Treaty established a comfortable working relationship between the Church (in this case, more exactly, Vatican City) and the State (in this case, Italy). The Treaty was signed by Benito Mussolini representing the Italian government, and Cardinal Pietro Gasparri, Vatican Secretary of State, representing Pope Pius XI. It was signed in the Lateran Palace (hence the name), and the treaty restored the civil sovereignty of the Pope as a monarch of an independent nation.
• The Financial Convention (3 articles), annexed to the treaty, which compensated the Holy See for the loss of the papal states; and
• The Concordat (45 articles), which dealt with the Roman Catholic Church’s ecclesiastical relations with the Italian State.
To commemorate the successful conclusion of the negotiations, Mussolini commissioned the Via della Conciliazione (Road of the Conciliation), which would symbolically link Vatican City to the heart of Rome.