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?

<P0-S0> The name Vatican city was first used in the Lateran Treaty, signed on 11 February 1929, which established the modern city - state. <P0-S1> The name is taken from Vatican Hill, the geographic location of the state. <P0-S2> ``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''. <SEP> <P1-S0> 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. <P1-S1> Its name refers to the mosaics of gold leaf behind glass tesserae that decorates the ceiling of the apse. <P1-S2> The plain exterior is of brick, with sandstone quoins and window framing. <P1-S3> 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> <P2-S0> in the following century ravenna, the capital of the western roman empire, became the center of late roman mosaic art (see details in ravenna section). <P2-S1> milan also served as the capital of the western empire in the 4th century. <P2-S2> in the st aquilinus chapel of the basilica of san lorenzo, mosaics executed in the late 4th and early 5th centuries depict christ with the apostles and the abduction of elijah; these mosaics are outstanding for their bright colors, naturalism and adherence to the classical canons of order and proportion. <P2-S3> the surviving apse mosaic of the basilica of sant'ambrogio, which shows christ enthroned between saint gervasius and saint protasius and angels before a golden background date back to the 5th and to the 8th century, although it was restored many times later. <P2-S4> the baptistery of the basilica, which was demolished in the 15th century, had a vault covered with gold-leaf tesserae, large quantities of which were found when the site was excavated. <P2-S5> in the small shrine of san vittore in ciel d'oro, now a chapel of sant'ambrogio, every surface is covered with mosaics from the second half of the 5th century. <P2-S6> saint victor is depicted in the center of the golden dome, while figures of saints are shown on the walls before a blue background. <P2-S7> the low spandrels give space for the symbols of the four evangelists. <SEP> <P3-S0> mission san juan capistrano (originally christened in 1716 as "la misión san josé de los nazonis" and located in east texas) was founded in 1731 by spanish catholics of the franciscan order, on the eastern banks of the san antonio river in present-day san antonio, texas. <P3-S1> the new settlement (part of a chain of spanish missions) was named for a 15th-century theologian and warrior priest who resided in the abruzzo region of italy. <P3-S2> the mission san juan was named after saint john of capestrano. <SEP> <P4-S0> 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.