Housed in the twin palaces of Palazzo Nuovo and Palazzo dei Conservatori standing on opposite sides of Michelangelo's piazza del Campidoglio, the Capitoline museums constitute the oldest public gallery in the world. Their collection was begun in 1471, when Pope Sixtus IV presented the Roman people with a group of classical sculptures. Sixtus' successors continued to enrich the collection with examples of ancient art (mostly sculptures) and, at a later date, some important Renaissance and post-Renaissance paintings. The entire collection was finally opened to the public in 1734, by Pope Clement XII. Many statues remain frustratingly label-less but there is a decent audioguide.
Entrance to the Musei Capitolini is by the Palazzo dei Conservatori, on the right as you come up Michelangelo's stairs. The courtyard contains what's left of the colossal statue of Constantine (the rest was made of wood) that originally stood in the Basilica of Maxentius in the Roman Forum.
Upstairs, the huge Sala degli Orazi e Curiazi(Room 1) is home to a statue (1635-40) by Bernini of his patron Urban VIII in which everything about the pope seems to be in motion. There's also a second-century BC gilded bronze Hercules. Room 2 (Sala dei Capitani) has late 16th-century frescoes of great moments in ancient Roman history. In Room 3 (Sala dei Trionfi), the first-century BC bronze of a boy removing a thorn from his foot, known as the Spinario, is probably an original Greek work. There's also a rare bronze portrait bust from the fourth or third century BC, popularly believed to be of Rome's first consul, Brutus.
Room 4 has long been home to the much-reproduced She-Wolf (lupa); as this guide went to press, authorities were considering moving the lupa - currently being restored - to the new Marcus Aurelius wing (see below). This statue is supposedly a fifth-century BC Etruscan bronze, though controversy is raging ; the suckling twins were added in the Renaissance (attributed to Antonio del Pollaiolo). In Room 5 (Sala delle Oche) is Bernini's pained-looking Medusa and an 18th-century bronze portrait of Michelangelo, believed to have been based on the great master's death mask. Room 6 (Sala delle Aquile) is frescoed with 16th-century Roman scenes amid faux-ancient 'grotesque' decorations. In Room 10 (Sala degli Arazzi) a marvellous marble group shows the Emperor Commodus dressing up as Hercules and being adored by two Tritons. Room 11 (Sala di Annibale) still has original early 16th-century frescoes that show Hannibal riding on an elephant of which Walt Disney would have been proud.
The second-century AD gilded bronze equestrian statue of Marcus Aurelius that for centuries stood in the centre of piazza del Campidoglio has now found a worthy home in an airy new wing of the museums which also contains large sections of a temple to Jupiter (Giove). Though the statue now on the plinth in the piazza outside is a 'perfect' computer-generated copy, it can't compare with the sheer delicacy and majesty of this original.
On the second floor, the Pinacoteca Capitolina (Capitoline art gallery) contains a number of significant works. The most striking is Caravaggio's St John the Baptist (1596; in the Sala di Santa Petronilla), who has nothing even remotely saintly about him. There's a weepy Penitent Magdalene (c1598) by Tintoretto, a Rape of Europa by Veronese, and an early Baptism of Christ (c1512) by Titian in Room 3. There are also some strangely impressionistic works by Guido Reni in Room 6, various busy scenes by Pietro da Cortona in the room named after him, and some luscious portraits by Van Dyck in the Galleria Cini, which also contains a self-portrait by Velázquez (1649-51) and some lovely early 18th-century scenes of Rome by Gaspare Vanvitelli. While you're up here, check out the café; the view from the terrace is spectacular.
To get to the other side of the Musei Capitolini, housed in the Palazzo Nuovo, visitors pass through the Tabularium, the ancient Roman archive building upon which the Palazzo Senatorio was built. The tufa vaults of the Tabularium date back to 78 BC, and the view from here over the Forum is simply breathtaking, particularly in the evocative light around sunset. Also visible in this area are the ruins of the Temple of Veiovis ('underground Jupiter').
Palazzo Nuovo houses one of Europe's most significant collections of ancient sculpture. The three ground-floor rooms contain portrait busts of Roman citizens, the endearing Vecchio ubriacone ('old drunk', part of Bacchus' entourage) and a huge sarcophagus with scenes from the life of Achilles, topped by two reclining second-century AD figures. Dominating the courtyard is the first-century AD river god known as Marforio, reclining above his little fountain.
Upstairs in the long gallery (Room 1), the wounded warrior falling to the ground with his shield is probably a third-century BC discus thrower's top half, turned on its side and given a new pair of legs in the 17th century. Room 2 (Sala delle Colombe) contains a statue of a little girl protecting a dove from a snake, a much-reworked drunken old woman clutching an urn of wine, and a dove mosaic from Hadrian's villa (Villa Adriana) at Tivoli. Room 3 (Gabinetto della Venere) is home to the coy first-century BC Capitoline Venus. This was probably based on Praxiteles' Venus of Cnodis, considered so erotic by the fourth-century BC inhabitants of Kos that one desperate citizen was caught in flagrante with it. In Room 4 (Sala degli Imperatori), portrait busts of emperors, their consorts and children are arranged chronologically, providing a good insight into changing fashions and hairstyles.
Next door in Room 5 (Sala dei Filosofi) are ancient portraits of philosophers and poets. Larger statues of mythical figures grace the huge Salone (Room 6). Room 7 (Sala del Fauno) is named after an inebriated faun carved from rosso antico marble in the late second century BC; the smirking, pointy-eared statue inspired Nathaniel Hawthorne's The Marble Faun. In Room 8 (Sala del Gladiatore) is the moving Dying Gaul, probably based on a third-century BC Greek original. Many ancient sculptures long hidden in the storerooms of the Musei Capitolini can now be seen at the Centrale Montemartini.