Question: When did the location of the basilica that is named after the same saint as the San Pietro in Ciel d'Oro become its own country?

Knowledge 1: San Pietro in Ciel d'Oro
San Pietro in Ciel d'Oro (Italian for "Saint Peter in Golden Sky") is a Roman Catholic basilica (and a former cathedral) of the Augustinians in Pavia, Italy, in the Lombardy region. Its name refers to the mosaics of gold leaf behind glass tesserae that decorates the ceiling of the apse. The plain exterior is of brick, with sandstone quoins and window framing. The paving of the church floor is now lower than the modern street level of Piazza San Pietro in Ciel d'Oro, which lies before its façade. [SEP] Knowledge 2: St. Peter's Basilica
The Papal Basilica of St. Peter in the Vatican (Italian: Basilica Papale di San Pietro in Vaticano), or simply St. Peter's Basilica (Latin: Basilica Sancti Petri), is an Italian Renaissance church in Vatican City, the papal enclave within the city of Rome. [SEP] Knowledge 3: Vatican City
The name Vatican city was first used in the Lateran Treaty, signed on 11 February 1929, which established the modern city - state. The name is taken from Vatican Hill, the geographic location of the state. ``Vatican ''is derived from the name of an Etruscan settlement, Vatica or Vaticum meaning garden, located in the general area the Romans called vaticanus ager,`` Vatican territory''.
Knowledge 1: San Pietro in Ciel d'Oro
San Pietro in Ciel d'Oro (Italian for "Saint Peter in Golden Sky") is a Roman Catholic basilica (and a former cathedral) of the Augustinians in Pavia, Italy, in the Lombardy region. Its name refers to the mosaics of gold leaf behind glass tesserae that decorates the ceiling of the apse. The plain exterior is of brick, with sandstone quoins and window framing. The paving of the church floor is now lower than the modern street level of Piazza San Pietro in Ciel d'Oro, which lies before its façade. [SEP] Knowledge 2: Old St. Peter's Basilica
St. Peter's Basilica Basilica Sancti Petri 19th - century drawing of St. Peter's Basilica as it is thought to have looked around 1450. The Vatican Obelisk is on the left, still standing on the spot where it was erected on the orders of the Emperor Caligula in 37 A.D. Basic information Geographic coordinates 41 ° 54 ′ 8 ''N 12 ° 27 ′ 12'' E ﻿ / ﻿ 41.90222 ° N 12.45333 ° E ﻿ / 41.90222; 12.45333 Coordinates: 41 ° 54 ′ 8 ''N 12 ° 27 ′ 12'' E ﻿ / ﻿ 41.90222 ° N 12.45333 ° E ﻿ / 41.90222; 12.45333 Affiliation Roman Catholic Country Papal States Year consecrated c. 360 Ecclesiastical or organizational status Major basilica Architectural description Architectural style Ancient Roman architecture Groundbreaking 326 - 333 (326 - 333) Completed c. 360 (c. 360) [SEP] Knowledge 3: Vatican City
The name Vatican city was first used in the Lateran Treaty, signed on 11 February 1929, which established the modern city - state. The name is taken from Vatican Hill, the geographic location of the state. ``Vatican ''is derived from the name of an Etruscan settlement, Vatica or Vaticum meaning garden, located in the general area the Romans called vaticanus ager,`` Vatican territory''.
Knowledge 1: San Pietro in Ciel d'Oro
San Pietro in Ciel d'Oro (Italian for "Saint Peter in Golden Sky") is a Roman Catholic basilica (and a former cathedral) of the Augustinians in Pavia, Italy, in the Lombardy region. Its name refers to the mosaics of gold leaf behind glass tesserae that decorates the ceiling of the apse. The plain exterior is of brick, with sandstone quoins and window framing. The paving of the church floor is now lower than the modern street level of Piazza San Pietro in Ciel d'Oro, which lies before its façade. [SEP] Knowledge 2: Old St. Peter's Basilica
St. Peter's Basilica Basilica Sancti Petri 19th - century drawing of St. Peter's Basilica as it is thought to have looked around 1450. The Vatican Obelisk is on the left, still standing on the spot where it was erected on the orders of the Emperor Caligula in 37 A.D. Basic information Geographic coordinates 41 ° 54 ′ 8 ''N 12 ° 27 ′ 12'' E ﻿ / ﻿ 41.90222 ° N 12.45333 ° E ﻿ / 41.90222; 12.45333 Coordinates: 41 ° 54 ′ 8 ''N 12 ° 27 ′ 12'' E ﻿ / ﻿ 41.90222 ° N 12.45333 ° E ﻿ / 41.90222; 12.45333 Affiliation Roman Catholic Country Papal States Year consecrated c. 360 Ecclesiastical or organizational status Major basilica Architectural description Architectural style Ancient Roman architecture Groundbreaking 326 - 333 (326 - 333) Completed c. 360 (c. 360) [SEP] Knowledge 3: St. Peter's Basilica
The Papal Basilica of St. Peter in the Vatican (Italian: Basilica Papale di San Pietro in Vaticano), or simply St. Peter's Basilica (Latin: Basilica Sancti Petri), is an Italian Renaissance church in Vatican City, the papal enclave within the city of Rome.

Answer: 11 February 1929