The Vatican palaces are an irregular mass of three-story and four-story buildings, built on long, plain lines and broken by additions and alterations. The papal residence and offices occupy the portion near the colonnade, and the rest is given over to museums and the Vatican Library. The Vatican museums are among the most important in the world; they are the Museo Pio-Clementino, founded in the 18th cent. and containing one of the world's great collections of antiquities; the Chiaramonti Museum, founded in the early 19th cent. and holding a collection of Greek sculptures and Renaissance imitations; the Braccio Nuovo, considered by many to be the most beautiful of all the museums; the Egyptian Museum and the Etruscan Museum, opposite the Braccio Nuovo; and the Pinacoteca Vaticana (opened in 1932), which contains paintings by Giotto, Guercino, Caravaggio, Poussin, and others.
The museums, however, house only part of the Vatican's treasure, for many of the Renaissance and modern paintings are found in the galleries surrounding the various courtyards, such as the Cortile del Belvedere and the Cortile San Damasco. Adjoining the Cortile San Damasco is the building containing the Borgia apartments on the first floor and the Raphael rooms on the second. The works of Raphael and his followers in the building make it one of the most famous artistic monuments in the world. The Vatican Library lies all along the western side of the Giardino della Pigna and Cortile del Belvedere. It is one of the world's richest repositories of ancient and medieval manuscripts in many languages. The principal chapel in the Vatican is the Sistine Chapel, the ceiling of which was painted (1508–12) by Michelangelo.