The Sistine Chapel was built during the papacy of Sixtus IV (1471-1484), from where it gets its name. It had two functions. One was religious, as a private chapel of the Pope and the second was defensive, forming part of the prominent fortified group of buildings around the Papagayo patio which made up the oldest part of the Papal palaces. The Sistine Chapel was built on the site of the Magna Chapel which formed part of the palace constructed by Pope Nicholas III. The present building consists of an underground chamber, a mezzanine and the chapel, over which there is a spacious attic area. The ground plan of the chapel is rectangular, without an apse and measures 134.32 ft (40.94m) by 48.99 ft (13.41m) and is 67.91 ft (20.70m) high. It is covered by a truncated barrel vault with small lateral vaults that correspond to the windows which illuminate the chapel. In the original decoration scheme the vault was covered with a starry sky painted by Piero Matteo d'Amelia, while the most important masters of the time painted frescos on the sidewalls. In the 1480s Perugino was summoned to decorate the altar wall but his work has been hidden behind the Last Judgement. Later, Botticelli, Ghirlandaio, Signorelli and Cosimo Rosselli arrived along with their assistants to paint frescos dedicated to Jesus and Moses. The frescos were done very quickly and seem to have been finished by mid-decade, finished off with fake curtains and a Papal portrait gallery. When [Julius II#PERSONAS#8] became Pope in 1503, he decided to enhance the vault's decoration, and six years later he gave the commission to Michelangelo, who took over three years to complete the task. Michelangelo worked on his frescos in three periods. The first period was between January and September of 1509; the second between September of 1509 and September of 1510; and the third was between January and August of 1511. He worked alone without any help from assistants and did not allow anyone to enter the chapel whilst it was being painted. It would appear that Julius II's original project consisted of a series of the Twelve Apostles as the subject for the ceiling, but it was soon replaced by a more elaborate scheme that represented various themes from the Old Testament, along with a series of Sibyls and Prophets who spoke of the coming of Christ. In the lunettes over the windows and in the pendentives above these Michelangelo painted Christ's ancestors, while in the vault's spandrels he painted four stories narrating the salvation of the nation of Israel. The centre of the ceiling was divided into nine bays, each one representing a scene from Genesis, alternating large spaces with smaller ones filled with the Ignudi, pairs of naked youths that were in keeping with the classical statuary. The Creation of Light, the Creation of the Planets and the Stars, the Creation of the Universe World, the Creation of Adam, the Creation of Eve, the Original Sin and the Expulsion from Paradise, the Sacrifice of Noah, the Flood and the [Drunkenness of Noah#CUADROS#6995] are depicted across the vault, distributed in an elaborate painted architectural framework of pilasters and entablatures. Michelangelo covered all the space with paint in an attempt to deceive the onlooker, copying the vaults of Roman MONUM_enents. Michelangelo painted the stories in reverse order to how they appear in Genesis, and some experts have interpreted this as the soul's return to God, related to the Neo-Platonic philosophy that Michelangelo would have become acquainted with in the Palazzo Medici. The iconographic programme, however, did not come from the painter directly but would have had to receive the Pope's consensus and be assessed by some theological authority, before being subjected once again to the Pope's definitive approval. The result was one of the great masterpieces of European art. It has recently been restored and cleaned so that the spectator can admire the marvel and intensity of colour in Michelangelo's work, and his admiration for the naked human anatomy present in the whole project.