I am standing before the Pantheon, my eyes crinkled against the vivid Roman light, translating the inscription over the portico: M. Agrippa L. F. Cos tertium fecit: Marcus Agrippa, son of Lucius, third consul, made this.

He didn’t, in fact. Agrippa’s original temple was destroyed by fire in AD80 and this is a reconstruction at the time of the Emperor Hadrian. Nevertheless, it is an awe-inspiring achievement. The perfectly balanced cement dome, cast in one piece, is an astonishing feat of engineering. (Concrete was one of the many ways the Romans anticipated modern building techniques.)

But the Pantheon’s most singular feature is the oculus, the central porthole to the sky through which light – and the weather – penetrate the dim interior. When I last came here it was to research a novel. It was snowing, and I watched flakes like feathers drift down towards the guttering candles on the Christian altar, which now, somewhat awkwardly, supplants the ancient altars of the Greco/ Roman gods. (Pantheon in Greek means “all the gods”.)

Today, an early shower of rain has washed the undulating marble floor beneath this skylight to the gods to a yellow gleam. I am back to research another novel, this time concerning Freud. The Pantheon is hardly a secret, but like all works of genius its effects are mysterious. Freud, chief architect of the theory of the unconscious, had an unfathomable dread of this consummate piece of architecture, which seemingly prompted fears of his own death.

When he reached the city of his dreams, he wrote to his wife: “Midday, opposite the Pantheon. This is what I have been afraid of for years.”

But Rome is a city that evokes disturbing emotions, which is why so many writers have pressed it into service. Pondering this, I thread one of the cobbled alleys that runs north from the Pantheon, past the alluring eatery where the local workforce eat behind closed shutters to ward off unwelcome tourists, making my way towards the Capitol Hill, which overlooks the Forum. The prodigious Michelangelo’s theatrical stairway mounts to an elegant piazza, also his design, where brides, posing for wedding photographs, daringly expose gartered thighs to the sober bronze replica of the equestrian statue of the philosopher emperor Marcus Aurelius. (This escaped demolition by pious “reformers” only by being mistaken for the Christian emperor Constantine.)

On either side of the piazza are the two palazzi that house the Capitoline Museum, where you may see Marcus Aurelius’s original and the bronze Etruscan wolf, with the ugly later accretions of Romulus and Remus. But my mind runs to another famous statue, and Isabel Archer, heroine of Henry James’s A Portrait of a Lady. “The blinds were partly closed in the windows of the Capitol, and a clear, warm shadow rested on the figures and made them more perfectly human. Isabel sat there a long time, under the charm of their motionless grace, seeing life between their gazing eyelids and purpose in their marble lips . . . An occasional tourist came into the room, stopped and stared a moment at the Dying Gladiator, and then passed out of the other door, creaking over the smooth pavement.”

The Dying Gladiator prepares us for the emotional death that Isabel is about to risk, and death is a theme that is evoked everywhere in Rome. From my vantage point on the Capitol, I am gazing across the Forum to the skeletal ruin of the Colosseum. I seem alone in preferring to avoid this most famous, and gory, of all sites.

Before it, at the other end of the Forum, I spy another celebration of humankind’s will to destroy: the neat Arch of Titus, beloved of Romantic19th-century amateur artists, raised to commemorate the destruction of Jerusalem and a reminder that present political grievances have long roots in the past.

I turn right, down the perilously slippery stones of the Via della Consolazione, the Road of Consolation, so called as it was the route to the Tarpeian Rock, where traitors were thrown to their death. I am bound for one of Rome’s least-known churches, the oratory of S. Giovanni Decolatto (St John the Beheaded), across the way from the Piazza della Consolazione on the Via della Misericordia. The original confraternity was dedicated to the care of prisoners. The brothers visited the condemned, staying with them in their last hours of life.

The socially conscious Dickens apparently didn’t blench from watching an execution there. The bodies of the unfortunates were interred in the church’s cloister. This is still the home of an order of nuns, who maintain the tradition of care for prisoners. If you are in Rome on June 24, try to attend the beautiful service, in the dim light of the rarely visited 16th-century church, when the public are allowed access to commemorate the feast day of the executed saint.

From here I continue my pilgrimage, this time to honour a quieter, though no less poignant, death. The consumptive Keats came to Rome to save his health, and died here, aged 25, in the rooms he took in a house on the Spanish Steps. You can see the tiny room in which he died, and a good replica of his bed and writing desk in the house, which is now the Keats and Shelley museum. I walk to Keats’s burial place in the “nonCatholic” cemetery. It’s a fair trek and you can take a bus or taxi, but I prefer to saunter through the leafy suburbs of the Aventino to the Piazza Albania and then down the Viale della Piramide Cestia, named for what is surely the oddest monument to death in Rome. A pyramid covers the tomb of a Roman nonentity, Caius Cestius. His prominent memorial overlooks the cemetery, just outside the old city walls, where cats threaten to outnumber the peaceful inmates. Here, in a corner of the tree-filled cemetery, you may find Keats’s modest memorial. He was so discouraged by adverse criticism and his lack of reputation that he wrote his own epitaph: Here lies One Whose Name was writ in Water.

The butterfly is the ancient symbol of psyche, the soul, and sitting under the pine that shades the grave, eating my lunch of fat black grapes and white peaches, amid fluttering fritillary butterflies, I recall lines from the Ode to Psyche: Yes, I will be thy priest, and build a fane In some untrodden region of my mind, Where branchèd thoughts, new grown with pleasant pain, Instead of pines shall murmur in the wind.

If we have eyes and ears for them, the dead speak to us still – and nowhere more compellingly than in Rome.

Salley Vickers’s The Other Side of You is published by HarperPerrenial (£7.99). Where Three Roads Meet will be published in November by Canongate (£12.99).

Where to stay

BY Will Hide

Grand Hotel de la Minerve
A luxury five-star hotel in an impressive 17th-century palace, close to the Pantheon. Details: 00 39 06 69 52 01, www.grandhoteldelaminerve.it. Doubles from £319, excluding breakfast.

The View at the Spanish Steps
A small luxury hotel (three rooms, one suite) on via Condotti with superb views from the roof garden. The sister Inn at the Spanish Steps, almost next door, is larger but no less sumptuous. Details: 69 92 56 57, www.theviewatthespanishsteps.com, B&B doubles from £305.

Radisson SAS
This large (232 bedrooms) ultra-modern building is close to Rome’s main train station, with good bus, metro and tram links to the rest of the city. In summer, it has one bonus over many other hotels in the capital – a large, rooftop pool. All rooms have free internet access. Details: 44 48 41, www.rome.radissonsas.com, doubles from £105.

Hotel Navona
This one-star family-run pensione is in a lovely old palazzo tucked away down a cool, dark side street. Room sizes vary, as do the views, but the location, just behind Rome’s most beautiful square, is unbeatable. It’s still quiet enough here to offer some peace after a long day thumping the city streets. Details: 686 4203, www.hotelnavona.com, doubles from £92.

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