Vatican Museums. The immense collections housed here are so rich that unless you are an art history buff you will probably just want to skim the surface, concentrating on pieces that strike your fancy. The Sistine Chapel is a must, of course, and that's why you may have to wait in line to see it; after all, every tourist in Rome has the same idea. Pick up a leaflet at the main entrance to the museums to see the overall layout. The Sistine Chapel is at the far end of the complex, and the leaflet charts two abbreviated itineraries through other collections to reach it. You can rent a taped commentary (EUR4, about 90 minutes) in English for the Sistine Chapel, the Stanze di Raffaello, and the other main attractions. Or you can book a guided tour with the Guided Visit to Vatican Museums Office (PHONE: 06/69884676). Phone at least a day in advance. Cost, including entrance fee, is EUR16.50.

The exhibition halls of the Biblioteca Vaticana (Vatican Library) are bright with frescoes and contain a sampling of the library's rich collections of precious manuscripts. Room X, the Room of the Aldobrandini Marriage, holds a beautiful Roman fresco of a nuptial rite. More classical statues are on view in the new wing. At the Quattro Cancelli you'll find the cafeteria. The Pinacoteca (Picture Gallery) displays works by such artists as Giotto (circa 1266-1337), Fra Angelico, and Filippo Lippi (circa 1406-69), and Raphael's exceptional Transfiguration, Coronation and Foligno Madonna.

The Stanze di Raffaello (Raphael Rooms) are second only to the Sistine Chapel in artistic interest -- and draw crowds comparable to the Sistine's as well. In 1508 Pope Julius II employed Raphael, on the recommendation of Bramante, to decorate the rooms with biblical scenes. The result was a Renaissance tour de force. Of the four rooms, the second and third were decorated mainly by Raphael. The others were decorated by Giulio Romano (circa 1499-1546) and other assistants of Raphael; the first room is known as the Stanza dell'Incendio, with frescoes of the fire (incendio) in the Borgo neighborhood by Romano.

The frescoed Stanza della Segnatura (Room of the Signature), where papal bulls were signed, is one of Raphael's finest works; indeed, they are thought by many to be some of the finest paintings in the history of Western art. This was Julius's private library, and the room's use is reflected in the frescoes' themes, philosophy and enlightenment. A paradigm of High Renaissance painting, the works here demonstrate the revolutionary ideals of the time: naturalism (Raphael's figures lack the awkwardness of those painted only a few years earlier); humanism (the idea that human beings are the noblest and most admirable of God's creations); and a profound interest in the ancient world, the result of the 15th-century rediscovery of classical antiquity. Theology triumphs in the fresco known as the Disputa, or Debate on the Holy Sacrament. The School of Athens glorifies some of philosophy's greats, including Plato and Aristotle at the fresco's center. The pensive figure on the stairs is thought to be modeled after Michelangelo, who was painting the Sistine ceiling at the same time Raphael was working here. Michelangelo does not appear in preparatory drawings, so Raphael may have added his fellow artist's portrait after admiring his work.

The tiny Cappella di Nicholas V (Chapel of Nicholas V) is aglow with frescoes by Fra Angelico (1387-1455), the Florentine monk whose sensitive paintings were guiding lights for the Renaissance. The Appartamento Borgia (Borgia Apartment) is worth seeing for the elaborately painted ceilings, designed and partially executed by Pinturicchio. Among the frescoes, look for the Borgia's family emblem, the bull, and for the blond Lucrezia, the Borgia pope's daughter, posing piously as St. Catherine.

In 1508, while Raphael was put to work on his series of rooms, the redoubtable Pope Julius II commissioned Michelangelo to paint single-handedly the more than 10,000-square-foot ceiling of the Cappella Sistina (Sistine Chapel). The task cost the artist four years of mental and physical anguish. It's said that for years afterward Michelangelo couldn't read anything without holding it up over his head. The result, however, was the masterpiece that you now see, its colors cool and brilliant after restoration. Bring a pair of binoculars to get a better look at this incredible work (unfortunately, you're not allowed to lie down on the floor to study the frescoes above, the viewing position of choice in decades past; by the time you leave the chapel your neck may feel like Michelangelo's, so you may also want to study it -- to take a cue from 19th-century visitors -- with the aid of a pocket mirror).

The ceiling is in essence a painted Bible: Michelangelo's subject was the story of humanity before the coming of Christ. Although some of the frescoed panels are veritable stews of figures, others -- especially the depiction of God's outstretched hand giving Adam the spark of life in the Creation of Adam -- are forcefully simple, revealing how much Michelangelo brought to painting from the discipline of sculpture. In 1541, some 30 years after completing the ceiling, Michelangelo was commissioned to paint the Last Judgment on the chapel's altar wall. If the artist's ceiling may be taken as an expression of the optimism of the High Renaissance, the Last Judgment, by contrast, is a virtual guided tour through hell. The aged and embittered Michelangelo painted his own face on the wrinkled human skin in the hand of St. Bartholomew, below and to the right of the figure of Christ, which he clearly modeled on the Apollo Belvedere (on exhibit in the Vatican galleries). This is not surprising, since in the intervening years Rome had been sacked and pillaged by mercenary troops of Charles V in 1527, who used the Sistine Chapel as a stable.

In only a few years the grim Counter-Reformation began, and suddenly the nudity in Michelangelo's Last Judgment was so repugnant to the papal court that the artist Daniele da Volterra (1509-66) -- forever after known as il braghettone (the breeches-maker) -- was ordered to paint loincloths over the offending parts. Like the ceiling, the Last Judgment has been cleaned; the restoration was unveiled in April 1994, surprising viewers with its clarity and color. Was Michelangelo truly a master of vibrant color? Or is the "new" Sistine a travesty of the artist's intentions? Opinions remain divided, but most art historians believe the restoration is true to Michelangelo's original vision.

In all, the Vatican Museums offer a staggering foray into the realms of art and history -- so much that it's foolhardy to try to see all the collections in one day. COST: EUR12; free last Sun. of month.