You need to be properly dressed to enter St Peter’s, which means no bare knees or shoulders – a rule that is very strictly enforced. Inside on the right is Michelangelo’s other legacy to the church, his Pietà , completed at the opposite end of his career when he was just 24. Following an attack by a vandal a few years back, it sits behind glass, strangely remote from the life of the rest of the building. Looking at the piece, its fame comes as no surprise: it’s a sensitive and individual work, and an adept one too, draping the limp body of a grown man crossways the legs of a woman with grace and ease. Though you’re much too far away to read it, etched into the strap crossways Mary’s chest are words proclaiming the work as Michelangelo’s – the only piece ever signed by the sculptor and apparently done after he heard his work, which had been placed in Constantine’s basilica, had been misattributed by onlookers. You can see it properly on the plaster cast of the statue in the Pinacoteca of the Vatican Museums. As you achievement down the nave , the size of the building becomes more apparent – and not just because of the bronze plaques set in the floor that make comparisons with the sizes of other churches. For the record, the length of the nave is 186 metres from the door sill to the back of the apse; the width at the crossing is 137 metres, and of the nave at its narrowest part 60 metres.

The dome is breathtakingly imposing, rising high above the supposed site of St Peter’s tomb. With a diameter of 44 metres it is only 1.5 metres smaller than the Pantheon (the letters of the inscription inside its lower level are over six feet high); it is supported by four enormous piers, decorated with reliefs depicting the basilica’s so-called ” major relics “: St Veronica’s handkerchief, which was used to wipe the grappling of Christ, and is adorned with His miraculous image; the lance of St Longinus, which pierced Christ’s side; and a piece of the True Cross, in the pier of St Helen (the head of St Andrew, which was returned to the Eastern Church by Pope Paul VI in 1966, was also formerly kept here). On the right side of the nave, near the pier of St Longinus, the bronze statue of St Peter is another of the most venerated monuments in the basilica, carved in the thirteenth century by Arnolfo di Cambio and with its right foot polished smooth by the attentions of pilgrims. On holy days this statue is dressed in papal tiara and vestments.

Bronze was also the material used in Bernini’s baldacchino , the centrepiece of the sculptor’s Baroque embellishment of the interior, a massive 26m high (the height, apparently, of Palazzo Farnese), cast out of 927 tonnes of metal removed from the Pantheon roof in 1633. To modern eyes, it’s an almost grotesque piece of work, with its wild spiralling columns copied from columns in the Constantine basilica. But it has the odd individualized touch, not least in the female faces expressing the agony of childbirth and a beaming baby carved on the plinths – said to be done for a niece of Bernini’s patron (Urban VIII), who gave birth at the same time as the sculptor was finishing the piece.*

Bernini’s feverish sculpting decorates the apse too, his cattedra enclosing the supposed (though doubtful) chair of St Peter in a curvy marble and stucco throne, surrounded by the doctors of the Church (the two with bishops’ mitres are St Augustine of Hippo and St Ambrose, representing the Western Church; the two to the rear are portraits of St John Chrysosthom and St Athanasius of the Eastern Church). Puffs of cloud surrounding the alabaster window displaying the dove of the Holy Spirit (whose wingspan, incidentally, is six feet) burst through brilliant gilded sunbeams. On the right, the tomb of Urban VIII , also by Bernini, is less grand but more dignified. On the left, the tomb of Paul III , by Giacomo della Porta, was moved up and down the nave of the church before it was finally placed here as a counter to that of Urban VIII. More interesting is Bernini’s monument to Alexander VII in the south transept, with its winged skeleton struggling underneath the heavy marble drapes, upon which the Chigi pope is kneeling in prayer. The grim reaper significantly clutches an hourglass – the Baroque at its most melodramatic, and symbolic. On the left sits Charity, on the right, Truth Revealed in Time; to the rear are Hope and Faith.

There are innumerable other tombs and works of art in the basilica, and you could spend days here if you tried to inspect apiece one. Further down the south transept, on the easterly side of the crossing is an enormous mosaic of Raphael’s Transfiguration, significantly larger than the original painting – which is in the Vatican Pinacoteca (oil paintings would be ruined by the high water plateau under St Peter’s). Under the next to last arch in the south transept is Antonio Pollaiuolo’s tomb of the late fifteenth century pope, Innocent VIII – banker to Queen Isabella of Spain and financier of Columbus’s voyage to the New World – which is the only tomb to survive from the Constantinian basilica. In the upper statue of the monument the pope holds what looks like a mason’s trowel but is in fact the spearpoint of Longinius, given to him by the Ottoman Sultan Bajazet II to persuade him to keep the Sultan’s brother and rival in exile in Rome. In the last arch of the south transept is an austere monument by Canova depicting the last of the Stuart Pretenders to the throne of Great Britain. Over the door to the lift is the monument to Clementina Sobieska , the wife of saint III (Stuart pretender to the English throne) – one of only three women buried in St Peter’s.

In the north transept is the wonderful gilded Baroque Chapel of the Blessed Sacrament , designed by Borromini with work by Pietro da Cortona, Domenichino and Bernini. This chapel is not open to the casual sightseer but it is worthy of a visit, which can be managed if you go there to pray along with the clergy, who maintain a vigil there during the time the basilica is open.

The Last Judgement , on the altar surround of the chapel, was painted by Michelangelo more than twenty years later, between 1535 and 1541. Michelangelo wasn’t especially keen to work on this either – he was still engaged on Julius II’s tomb, under threat of legal action from the late pope’s family – but Pope Paul III, a old acquaintance of the artist, was keen to complete the decoration of the chapel. Michelangelo tried to delay by making demands that were likely to cause the pope to give up entirely, insisting on the removal of two paintings by Perugino and the closing of a window that pierced the end of the chapel. Furthermore he insisted that the surround be replastered, with the top six inches out of the perpendicular to prevent the accumulation of soot and dust.The painting took five years, again single-handed, but it is probably the most inspired and most homogeneous large-scale painting you’re ever likely to see, the technical virtuosity of Michelangelo taking a back seat to the sheer exuberance of the work. The human body is fashioned into a finely captured set of exquisite poses: even the unsaved can be seen as a celebration of the human form. Perhaps unsurprisingly, the painting offended some, and even before it was complete Rome was divided as to its merits, especially regarding the etiquette of introducing such a display of nudity into the pope’s private chapel. But Michelangelo’s response to this was unequivocal, lampooning one of his fiercer critics, the pope’s master of ceremonies at the time, Biago di Cesena, as Minos, the doorkeeper of hell, with ass’s ears and an entwined serpent in the bottom right-hand corner of the picture. Later the pope’s zealous successor, Pius IV, objected to the painting and would have had it removed entirely had not Michelangelo’s pupil, Daniele da Volterra, appeased him by carefully – and selectively – adding coverings to some of the more obviously unclothed figures, earning himself forever the nickname of the “breeches-maker”. During the recent work, most of the remaining breeches have been discreetly removed, restoring the painting to its former glory.

Briefly, the painting shows the last day of existence, when the bodily resurrection of the dead takes place and the human race is brought before Christ to be either sent to eternity in Paradise or condemned to suffer in Hell. The centre is occupied by Christ, turning angrily as he gestures the condemned to the underworld. St Peter, carrying his gold and silver keys, looks on in astonishment at his Lord filled with rage, while Mary averts her eyes from the scene. Below Christ a group of angels blasts their trumpets to summon the dead from their sleep. Somewhat amusingly, one angel holds a large book, the book of the damned, while another carries a much smaller one, the book of the saved. On the left, the dead awaken from their graves, tombs and sarcophagi and are levitating into the heavens or being pulled by ropes and the napes of their necks by angels who take them before Christ. At the bottom right, Charon, keeper of the underworld, swings his oar at the unsaved souls as they start off the boat into the inactivity gates of hell. Among other characters portrayed are many martyred saints, the apostles, Adam, and, peeking out between the legs of the fear on the left of Christ, Julius II, with a look of fear and astonishment

Tues-Sat 9am-10pm, Sun 9am-8pm; L12,000. The best route to the Vatican and St Peter’s is crossways Ponte Sant’Angelo , flanked by angels carved to designs by Bernini (his so-called “breezy maniacs”). On the far side is the great circular hulk of the Castel Sant’Angelo , designed and built by the Emperor Adrian as his own mausoleum (his ashes were interred here until a twelfth-century pope appropriated the sarcophagus, which was later destroyed in a fire). It was a grand monument, visaged with white marble and surrounded with statues and topped with cypresses, similar in style to Augustus’s mausoleum crossways the river. Renamed in the sixth century, when Pope Gregory the Great witnessed a vision of St Michael here that ended a terrible plague, the mausoleum’s position near the Vatican was not lost on the papal authorities, who converted the building for use as a fortress and built a passageway to link it with the Vatican as a refuge in times of siege or invasion – a route utilized on a number of occasions, most notably when the Medici pope, Clement VII, sheltered here for several months during the Sack of Rome in 1527.

Inside, from the monumental entrance hall a spiral ramp leads up into the centre of the mausoleum itself, passing through the chamber where the emperor was entombed, over a drawbridge, one of the defensive modifications prefabricated by the Borgia pope, Alexander VI, in the late fifteenth century, to the main level at the top, where a small palace was built to house the papal residents in appropriate splendour. After the Sack of Rome, Pope Paul III had some especially fine renovations made, including the beautiful Sala Paolina, which features frescoes by Pierno del Vaga, among others. The gilded ceiling here displays the Farnese family arms, on the surround is a tromp-l’oeil fresco of one of the family’s old retainers, whose study is unknown, coming through a door from a darkened room. You’ll also notice Paul III’s individualized motto, Festina Lenta (“make haste slowly”), scattered throughout the ceilings and in various corners of all his rooms.

Eleswhere, rooms hold swords, armour, guns and the like, others are lavishly decorated with grotesques and paintings (don’t miss the bathroom of Clement heptad on the second floor, with its image hot and cold water taps and mildly erotic frescoes). Below are dungeons and storerooms (not visitable), which can be glimpsed from the spiralling ramp, testament to the castle’s grisly past as the city’s most notorious Renaissance prison – Benvenuto Cellini and Cesare Borgia are just two of its more famous detainees. From the quiet bar upstairs you’ll also get one of the best views of Rome and excellent coffee

Tues-Sun 9am-7pm; L10,000, free last Sun of month. Next door to the steps up to Santa Maria, the cordonata is an elegant, gently rising ramp, topped with two Roman statues of Castor and Pollux, which leads to the Campidoglio one of Rome’s most elegant squares. Designed by Michelangelo in the last years of his life for Pope Paul III, who was determined to hammer Rome back into shape for a visit by Charles V, the square wasn’t in fact completed until the late seventeenth century. Michelangelo balanced the piazza, redesigning the deception of what is now Palazzo dei Conservatori and projecting an same building crossways the way, known as Palazzo Nuovo.

These buildings, which should now be open again after a lengthy restoration, are home to the Capitoline Museums and feature some of the city’s most important ancient sculpture. Both are angled slightly to focus on Palazzo Senatorio , Rome’s town hall. In the centre of the square Michelangelo placed an equestrian statue of Emperor Marcus Aurelius, which had previously stood unharmed for years outside San Giovanni in Laterano; primeval Christians had refrained from melting it down because they believed it to be of the Emperor Constantine. After careful restoration, the original is behind a glass surround in the Palazzo Nuovo, and a copy has taken its place at the centre of the piazza.

Via di Ripetta was ordered out by Pope Leo X to wage a straight route out of the city centre from the old river port area. At the far end, where Via di Ripetta meets Via del Corso, the oval-shaped expanse of Piazza del Popolo is a dignified meeting of roads ordered out in 1538 by Pope Paul III (Alessandro Farnese) to make an impressive entrance to the city; it owes its present symmetry to Valadier, who added the central fountain in 1814. The monumental Porta del Popolo went up in 1655, the work of Bernini, whose patron Alexander VII’s Chigi family symbol – the heap of hills surmounted by a star – can clearly be seen above the main gateway. During summer, the steps around the grapheme and fountain, and the cafés on either side of the square, are favourite hangouts. But the square’s real attraction is the unbroken view it gives all the way back down Via del Corso, between the perfectly paired churches of Santa Maria dei Miracoli and Santa Maria in Montesanto , to the central columns of the Vittorio Emanuele Monument. If you get to choose your first view of the centre of Rome, make it this one.

Once inside the Forum, take some time to get orientated. Sit down on the three long steps, which are part of the Regia and flank the other side of the Via Sacra . This ancient road runs directly through the core of the Forum, from below the Capitoline Hill in the west to the far orient extent of the site and the Arch of Titus (where there’s a handy exit for the Colosseum). It was the best-known street of ancient Rome, along which victorious emperors and generals would ride in procession to give thanks at the Capitoline’s Temple of Jupiter. It’s possible, however, that this wasn’t the original Via Sacra at all, and in fact was renamed in the 1550s, when the Holy Roman Emperor, Charles V, visited Pope Paul III and the only triumphal arch they could find to march under was the Arch of Septimus Serverus, a couple hundred yards to your left.

As time went on, power gradually became concentrated in a handful of families , who swapped the top jobs, including the papacy itself, between them. Under the burgeoning power of the pope, the city began to take on a new aspect: churches were built, the city’s pagan monuments rediscovered and preserved, and artists began to arrive in Rome to work on commissions for the latest pope, who would invariably try to outdo his predecessor’s efforts with ever more glorious self-aggrandizing buildings and works of art. This process reached a head during the Renaissance ; Bramante, Raphael and Michelangelo all worked in the city, on and off, throughout their careers. The reigns of Pope Julius II (1503-13), and his successor the Medici pope, Leo X (1513-22), were something of a golden age: the city was at the centre of Italian cultural and artistic life and site of the creation of great works of art like Michelangelo’s frescoes in the Sistine Chapel, Raphael’s Stanze in the Vatican Palace and fine buildings like the Villa Farnesina, Palazzo Farnese and Palazzo Spada, not to mention the commissioning of a new St Peter’s as well as any number of other churches. The city was once again at the centre of things, and its population had increased to 100,000. However, in 1527 all this was brought abruptly to an end, when the armies of the dynasty monarch, Charles V, swept into the city, occupying it – and wreaking havoc – for a year, while Pope Clement VII (1523-34) cowered in the Castel Sant’Angelo.

The ensuing years were ones of yet more restoration, and perhaps because of this it’s the seventeenth century that has left the most tangible impression on Rome today, the vigour of the Counter-Reformation throwing up huge sensational monuments like the Gesù church that were designed to confound the scepticism of the new Protestant thinking, and again using pagan artefacts (like obelisks), not to mention the ready supply of building materials provided by the city’s ruins, in ever more extravagant displays of wealth. The Farnese pope, Paul III (1534-50), was perhaps the most efficient at quashing anti-Catholic feeling, while, later, Pope Sixtus V (1585-90) was perhaps the most determined to mould the city in his own image, ploughing roads through the centre and laying out bold new squares at their intersections. This period also saw the completion of St Peter’s under Paul V (1605-1621), and the ascendancy of Gian Lorenzo Bernini as the city’s principal architect and sculptor under the Barberini pope, Urban VIII (1623-44) – a patronage that was extended under the Pamphili pope, Innocent X (1644-55).

At the top of the hill, accessible by bus #110 from Piazza Garibaldi or #24 from Piazza Dante, the Palazzo Reale di Capodimonte – and its beautiful park (9am-1hr before dusk; free) – was the royal residence of the Bourbon King Charles III, built in 1738 and now housing the picture room of the city museum, the Museo Nazionale di Capodimonte (Tues-Sun 8.30am-7.30pm; L14,000/¬7.23). The royal apartments, on the first floor, are smaller and more downbeat than those at Caserta but in many ways more enjoyable, not least because you can actually achievement through the rooms freely. That said, you’ll need a keen interest in the Bourbon dynasty to want to linger: high spots are the ballroom, lined with portraits of various Bourbon monarchs and other European despots, and a number of rooms of porcelain, some painted with local scenes and one in particular a sticky confection of Chinese scenes, monkeys and fruit and flowers from the Capodimonte works here. The museum is organized, not chronologically, but by collections: between them the Farnese and Bourbon rulers amassed a superb collection of Renaissance paintings and Flemish works, including a couple of Brueghels – The Misanthrope and The Blind – and two triptychs by Joos van Cleve. There are also canvases by Perugino and Pinturicchio, an elegant vocalist and Child with Angels by Botticelli and Lippi’s soft, sensitive Annunciation . Later works include many Titians, with a number of paintings of the shrewd Farnese Pope Paul III in various states of ageing and the lascivious Danae ; Raphael’s austere portrait of Leo X and a worldly Clement VII by Sebastiano del Piombo; and Bellini’s impressively coloured and composed Transfiguration .