It's a brisk ten-minute walk around the Vatican walls from St Peter's to the Vatican Museums.
Begun by Pope Julius II in 1503, this immense collection represents the accumulated fancies and obsessions of a long line of strong, often contradictory personalities. The popes' unique position allowed them to obtain treasures on favourable terms from other collectors, and artists often had little choice as to whether they accepted papal commissions.
One-way routes cater for anything from a dash to the Sistine Chapel to a five-hour plod around the lot (if opening hours permit). There are also a number of itineraries for wheelchair users, with facilities en route. Wheelchairs can be borrowed at the museum: you can't book them, but call ahead (06 6988 3860) to check there's one free. The following are selected highlights from the collections (in alphabetical order).
This six-room suite, known as the Borgia Rooms, was adapted for the Borgia Pope Alexander VI (1492-1503) and decorated by Pinturicchio with a series of frescoes on biblical and classical themes. In 1973 some 50 rooms adjoining the Borgia Apartments were renovated to house the Collezione d'Arte Religiosa Moderna.
Cappella Sistina (Sistine Chapel)
The world's most famous frescoes cover the ceiling and one immense wall of the Cappella Sistina, built for Sixtus IV in 1473-84. For centuries it has been used for papal elections. In the 1980s and '90s, the 930 sq m (10,000 sq ft) of Creation - on the ceiling - and the Last Judgement - on the wall behind the altar - were subjected to the most controversial restoration job of all time. The result is very blue.
In 1508 Michelangelo was commissioned to paint a simple decoration on the ceiling of the Sistine Chapel. Julius II may have been egged on to employ a sculptor with no experience in fresco by his architect Bramante, who was jealous of the pope's admiration for Michelangelo and desperately wanted to see him fail. Michelangelo responded by offering to do far more than mere decoration, and embarked upon his massive venture alone. He spent the next four and a half years standing (only Charlton Heston lay down) on 18m-high (60ft) scaffolding with paint and plaster dripping into his eyes. Despite a fairly handsome payment (in four years he earned as much as a regular artist could expect to earn in 15), he complained to his brother in 1511, 'I could well say that I go naked and barefoot.' Under pressure from the dying Julius II (syphilis got him in the end) to finish as quickly as possible, Michelangelo complained in another letter: 'I have no friends and no need of them; I wish simply to eat a hot meal in peace.'
The ceiling work was completed in 1512, just seven months before the death of Julius, and is exemplary of the confident pursuit of beauty of the High Renaissance. Beginning at the Last Judgment end, scenes depict the Separation of Light from Darkness, the Creation of Sun, Moon and Planets, the Separation of Land and Sea and the Creation of Fishes and Birds; the Creation of Adam, the Creation of Eve, the Temptation and Expulsion from Paradise; the Sacrifice of Noah (which should have appeared after the Flood, but for lack of space), the Flood and the Drunkenness of Noah. Michelangelo painted these scenes in reverse order, beginning with Noah's drunkenness. They are framed by monumental figures of Old Testament prophets and classical sibyls foretelling the birth of Christ.
Twenty-three years later, aged 60, Michelangelo was dragged back by Paul III in 1535. Between the completion of the ceiling and the beginning of the wall, Rome had suffered. From 1517, the Protestant Reformation threatened the power of the popes, and the sack of the city in 1527 was seen by Michelangelo as the wrath of God descending on the corrupt city. The Last Judgment dramatically reflects this gloomy and pessimistic atmosphere. Hidden among the larger-than-life figures that stare, leer and cry out from their brilliant ultramarine background, Michelangelo painted his own frowning, miserable face on the wrinkled human skin held by St Bartholomew, below and to the right of the powerful figure of Christ the Judge. In 1555 Paul IV objected to the nudity and added modest loincloths, removed in the recent restoration.
Before Michelangelo set foot in the chapel, the stars of the 1480s had created the paintings along the walls. On the left-hand wall (as you look at the Last Judgment) are: the Journey of Moses by Perugino; Events from the Life of Moses by Botticelli; Crossing the Red Sea and Moses Receives the Tablets of the Law by Cosimo Rosselli; The Testament of Moses by Luca Signorelli; and The Dispute over Moses' Body by Matteo da Lecce. On the right-hand wall are The Baptism of Christ by Perugino; The Temptations of Christ by Botticelli; The Calling of the Apostles by Ghirlandaio; Handing over the Keys by Perugino; The Sermon on the Mount and The Last Supper by Cosimo Rosselli; and The Resurrection by Hendrik van den Broeck (van den Broeck and Lecce replaced the paintings lost after the collapse of the Popes' entrance in 1565). The portraits are by the same masters.
Founded by Pius VII in the early 19th century and laid out by the sculptor Canova, this is an eclectic collection of Roman statues, reliefs and busts. Don't miss the replica of a Greek statue by Polyeuctos of stuttering orator Demosthenes or the copy of a Resting Satyr by the Greek sculptor Praxiteles.
Gallerie dei Candelabri & degli Arazzi
The long gallery studded with candelabra contains Roman marble statues, while the next gallery has ten huge tapestries (arazzi), woven by Flemish master Pieter van Aelst from the cartoons by Raphael that are now in London's Victoria & Albert Museum.
Galleria delle Carte Geografiche
Pope Gregory XIII (who was responsible for introducing the Gregorian calendar) had a craze for astronomy, and was responsible for this 120m-long (394ft) gallery, with its Tower of the Winds observation point at the north end. Ignazio Danti of Perugia drew the maps, which were then frescoed (1580-83), and show each Italian region, city and island with extraordinary precision.
Founded by Gregory XVI in 1839, in rooms which are partly decorated in Egyptian style, this is a representative selection of ancient Egyptian art from 3000 BC to 600 BC. It includes statues of a baboon god, painted mummy cases and a marble statue of Antinous, Emperor Hadrian's lover, who drowned in Egypt and was declared divine by the emperor. A couple of real mummies help make this the most exciting bit of the whole Vatican if you have grisly-minded kids in tow.
Founded in 1837 by Gregory XVI, and enlarged in the 20th century, this collection contains Greek and Roman art as well as Etruscan masterpieces, including the contents of the Regolini-Galassi Tomb (c650 BC), the Greek-inspired fourth-century BC Mars, and the fifth-century BC Young Man and Small Slave.
This collection of Roman and neo-Attic sculpture has been housed here since 1970. Highlights include the beautifully draped statue of Sophocles from Terracina, a trompe l'oeil mosaic of an unswept floor and the wonderfully elaborate Altar of Vicomagistri.
In the late 18th century Pope Clement XIV and his successor Pius VI began the world's largest collection of classical statues; it now fills 16 rooms. Don't miss the first-century BC Belvedere Torso by Apollonius of Athens; the Apollo Sauroctonos, a Roman copy of the bronze Lizard Killer by Praxiteles; and, in the octagonal Belvedere Courtyard, the exquisite Belvedere Apollo and Laocoön, the latter being throttled by the sea serpents Athena had sent as punishment for warning the Trojans to beware of the wooden horse.
Founded by Pius VI in the late 18th century, the Pinacoteca (picture gallery) includes many of the pictures that the Vatican hierarchy managed to recover from Napoleon after their forced sojourn in France in the early 19th century. The collection ranges from early paintings of the Byzantine School and Italian primitives to 18th-century Dutch and French old masters, and includes Giotto's Stefaneschi Triptych; a Pietà by Lucas Cranach the Elder; several delicate Madonnas by Fra Filippo Lippi, Fra Angelico, Raphael and Titian; Raphael's very last work, The Transfiguration; Caravaggio's Entombment; and a chiaroscuro St Jerome by Leonardo da Vinci.
Pio Cristiano Museum
The upper floor of the Museo Paolino is devoted to a collection of early Christian antiquities, mostly sarcophagi carved with reliefs of biblical scenes.
Stanze di Raffaello, Loggia di Raffaello
& Cappella di Niccolò V
The Raphael Rooms were part of Nicholas V's palace, and were originally decorated by Piero della Francesca. Julius II then let Perugino and other Renaissance masters loose on them. He later discovered Raphael, and gave the 26-year-old carte blanche to redesign four rooms of the Papal Suite. The order of the visit changes from time to time; if possible, try to see the rooms in the order in which they were painted. The Study (Stanza della Segnatura) was the first one Raphael tackled (1508-11), and features philosophical and spiritual themes - the triumph of Truth, Good and Beauty. Best known is the star-packed School of Athens fresco, with contemporary artists as classical figures: Plato is Leonardo; the glum thinker with the big knees on the steps at the front - Heraclitus - is Michelangelo; Euclid is Bramante (note the letters RUSM, Raphael's signature, on his gold collar); and Raphael himself is on the far right-hand side just behind a man in white, believed to be his pupil Sodoma. Raphael next turned his hand to the Stanza di Eliodoro (1512-14), frescoed with The Expulsion of Heliodorus. The portrayal of God saving the temple in Jerusalem from the thieving Heliodorus was intended to highlight the divine protection enjoyed by Julius himself (the pope's portrait is shown twice: both as the priest of the temple in the centre wearing blue and gold, and as the red-capped figure carried on a bier on the left).
The Dining Room (Stanza dell'Incendio, 1514-17), painted after Julius' death, is dedicated to his successor, Leo X (the most obese of the Popes, he died from gout aged 38), and shows other (more virtuous) Pope Leos with the face of Leo X. The room is named for the Fire in the Borgo, which Leo IV apparently stopped with the sign of the cross. (Note the first church of St Peter's in the background).
The Reception Room (Sala di Constantino, 1517-24) was completed by Giulio Romano after Raphael's death in 1520, but was based on Raphael's sketches of the Church's triumph over paganism, and tells the legend of Constantine's miraculous conversion.
The long Loggia di Raffaello (almost never open to the public) has a beautiful view over Rome. Started by Bramante in 1513, and finished by Raphael and his assistants, it features 52 small paintings on biblical themes, and leads into the Sala dei Chiaroscuri (Gregory XIII obliterated Raphael's frescoes here, but the magnificent ceiling remains). The adjacent Cappella di Niccolò V (Chapel of Nicholas V, usually open), has outstanding frescoes of scenes from the lives of saints Lawrence and Stephen by Fra Angelico (1448-50).
The Vatican Library
Founded by Pope Nicholas V in 1450, this is one of the world's most extraordinary libraries, containing 100,000 medieval manuscripts and books, and over a million other volumes. It is open to students and specialists on application to the Admissions office (06 6987 9403, firstname.lastname@example.org).