The Vatican is located on the left bank of the Tiber River in Rome, where, according to tradition, Saint Peter, the first pope and the apostle to whom Christ had left in charge of his ministry, was martyred in 67 A.D. In 320–27 A.D. the emperor Constantine built a five-aisled basilica atop the early Christian necropolis that was Peter's resting place, with a shrine in the apse of the church to mark the location of Peter's tomb.
During the medieval decline of Rome and frequent barbarian invasions, popes had to protect the basilica and in the 800s Pope Leo IV began surrounding the future Vatican City with thick walls. The transfer of the papacy to Avignon in 1309 left the Vatican Hill unattended for 70 years, and St. Peter’s was abandoned and left subject to elements. When the popes returned, their top priority was to repair the church. The second was to build a permanent home for the Pope. Due to the lack of resources these changes were not going to be easy and would take time. In the mid-15th century it was decided that the old basilica should be rebuilt. Pope Nicholas V asked architect Bernardo Rossellino to start adding to the old church but this was quickly abandoned.
Serious work on St. Peter’s Basilica began under Pope Julius II, who gathered the resources and the will to carry out the project. Julius soon decided to hire famed architect Donato Bramante to tear down the Constantinian basilica and rebuild Saint Peter's entirely, an idea that was met with a lot of opposition from parties who felt that the old church, which had existed basically since the dawn of Christianity, should be preserved.
Bramante carried through very wrecklessly, destroying mosaics, frescoes, statues and even relics with such abandon that he earned the nickname, Maestro Ruinante or “Master Wrecker.” In Rome Bramante created the “Tempietto” in the Cloister of San Pietro in Montorio. This small circular temple marks the spot where St Peter was martyred and is thus the most sacred site in Rome. The building adapts the style apparent in the remains of the Temple of Vesta, the most sacred site of Ancient Rome. After Bramante’s death and many changes of plan, Michelangelo, as chief architect, reverted to something closer to Bramante’s original proposal. Steadily, the jumbled Vatican skyline was beggining to take shape.
The Sistine Chapel, just to the north of St. Peter’s, was commissioned by Pope Sixtus IV and built according to the dimensions of Solomon’s Temple in Jerusalem. It was finally completed in 1481. It was designed to be ,and still is, the pope's chapel and the site of papal elections. In 1481 Sixtus IV called to Rome the Florentine painters Sandro Botticelli, Domenico Ghirlandaio and Cosimo Rosselli and the Perugian Pietro Perugino to decorate the walls with frescoes. Luca Signorelli may have also been involved in the decoration. The fresco project took only 11 months, from July 1481 to May 1482. The Sistine Chapel was consecrated and dedicated to the Assumption of the Virgin on August 15, 1483. The Sistine ceiling was originally painted by Piero Matteo d'Amelia, who included a star-spangled sky. But Nearly 30 years after it was built, an artist named Michelangelo would begin painting his most famous