Emperors Underfoot: Augustus and the Buried Campus Martius of Rome

From the hall where Caesar was stabbed to the tomb of the heir who turned that murder into an empire: theatres, baths, a sundial and an altar of peace hidden under Rome's shopping streets

Rome · 11 stops · 27 min audio · Generated October 2026

1. 1. Largo Argentina: Where Caesar Fell

   Largo di Torre Argentina, 00186 Roma RM, Italy

   Listen · 2:50

   Lean on the railing and look down into the sunken square below the traffic: four temples, a scatter of broken columns, a few umbrella pines, and a surprising number of cats asleep on the warm stone. Up here is modern Rome, with its buses and trams. Down there is the ground Julius Caesar knew... and the last place he ever walked to.

   These are temples of the Republic, older than any emperor, and archaeologists still label them simply A, B, C and D, because nobody can say for certain which gods lived in them. The round one, temple B, is usually linked to Fortuna, the goddess of luck. They came to light between 1926 and 1929, when a whole medieval neighbourhood was knocked down for new roads, and the planners found, instead, an ancient sacred square.

   Look past the round temple to the back, where a long block of tufa foundations runs behind the columns. That is part of the Curia of Pompey, a meeting hall attached to Pompey's great theatre complex. On the Ides of March, 44 BC, the Senate was sitting there, and Caesar walked in despite the warnings. The historian Suetonius counted twenty-three stab wounds. Plutarch says he fell at the foot of a statue of Pompey, the rival he had defeated.

   And this is where our walk really begins. Caesar's adopted heir was his great-nephew Octavian, just eighteen years old. Within seventeen years he had defeated the assassins, then Mark Antony and Cleopatra, and taken a new name: Augustus. The hall where Caesar died was walled up and treated as a place of ill omen. Then Augustus turned this flat meadow by the river, the Campus Martius, into a showcase of his peace, his family and his own eternity.

   By the way, the name Argentina has nothing to do with South America. It comes from Argentoratum, the Latin name of Strasbourg, home city of Johannes Burckard, a papal master of ceremonies around 1500, whose tower house still stands on a corner nearby. The cats have been cared for by volunteers among the ruins for decades, and since 2023 new walkways let visitors go down among the temples themselves. Now head west along the main road, past the great dome of Sant'Andrea della Valle, and slip into the lanes on your left... where a street bends for no visible reason.

2. 2. Via di Grotta Pinta: Living Inside Pompey's Theatre

   Via di Grotta Pinta, 00186 Roma RM, Italy

   Walk slowly down this quiet lane and notice that the houses on one side do not run straight: they bend in a smooth, deliberate curve, as if someone had drawn them with a giant compass. Someone did. You are standing inside a Roman theatre, and these walls are built on top of its seats.

   This was the Theatre of Pompey, inaugurated in 55 BC, the first permanent stone theatre in Rome. Until then the Senate considered permanent theatres a danger to public morals, and audiences sat on temporary wooden stands. Pompey found a loophole. At the top of the seating he built a temple to Venus Victrix, so that, officially, the rows of seats were just a grand staircase leading up to a shrine. Behind the stage stretched gardens and colonnades, all the way to the hall where Caesar would die.

   When Rome shrank in the Middle Ages, nobody wasted such a magnificent ruin. Families built their houses straight into its vaults, and the curve of the auditorium survived as the curve of this street. The name Grotta Pinta, the painted grotto, probably remembers decorated chambers people found under their homes, and several cellars around here still have Roman concrete arches holding up their ceilings.

   And Augustus? He handled this building the way he handled everything. In his own account of his reign, the Res Gestae, he boasts that he restored the Theatre of Pompey at great expense... without inscribing his own name on it. Suetonius adds that he moved Pompey's statue out of the hall where Caesar was murdered and set it on a marble arch facing the theatre. Honour the defeated rival, advertise your own modesty, and let everyone notice. Modesty, used as a weapon.

   One last secret. In 1864, workers in the courtyard of a palace beside the lane, Palazzo Pio Righetti, found a gilded bronze Hercules nearly four metres tall, laid carefully in a pit lined with stone slabs carved with three letters, FCS: fulgur conditum, lightning buried here. The statue had been struck by lightning, and the Romans buried it like something sacred. It now stands in the Vatican Museums. From here, cross Corso Vittorio Emanuele, walk the whole length of Piazza Navona, and keep going out of its northern end.

3. 3. Stadium of Domitian: The Ghost Under Piazza Navona

   Via di Tor Sanguigna 3, 00186 Roma RM, Italy

   Step out of the northern end of Piazza Navona and peer through the openings below the pavement into a deep trench: travertine arches, brick walls, the stumps of great stairways. That is the Stadium of Domitian... and the elegant oval piazza you just crossed is its ghost.

   The emperor Domitian built it around 86 AD for Greek-style games: running, wrestling, boxing, the contests the Greeks called the agon. The track ran more than two hundred and fifty metres from end to end, and tens of thousands of spectators sat on its tiers. The piazza keeps the exact shape of the arena, and even its name descends from the stadium: in agone, at the games, slurred over the centuries by Roman tongues into Navona.

   Domitian was the son of Vespasian and the younger brother of Titus, a tireless builder and a deeply suspicious ruler. After a great fire in 80 AD swept the Campus Martius, it was largely his workmen who rebuilt it. In 96 he was stabbed to death in his own palace, and the Senate condemned his memory, hacking his name off inscriptions across the empire. His stadium simply carried on without him.

   Under the stands ran rows of arches, in Latin fornices, and ancient writers tell us prostitutes worked in arches like these. That is where the word fornication comes from. Christian tradition places the martyrdom of a young girl, Agnes, right here: exposed in the arches, she was covered, the legend says, by her own miraculously growing hair. The church of Sant'Agnese in Agone, on the piazza, stands over the spot.

   For centuries Romans simply lived inside the stadium. Houses grew on top of the stands, and the old arena became a market and a festival ground. From the 17th to the 19th century the piazza was even flooded on summer weekends, so that carriages could splash through it, the so-called Lake of Piazza Navona. Now walk south-east through the lanes, toward the back of the Pantheon, to a street named after a doughnut.

4. 4. Arco della Ciambella: The Baths of Agrippa

   Via dell'Arco della Ciambella, 00186 Roma RM, Italy

   Find the great curved wall of brick and concrete squeezed between the houses of this narrow lane, a slice of a giant circle with modern windows punched into it and drainpipes running down its face. Romans have called it la ciambella, the doughnut, for centuries, and the street took its name.

   It is a fragment of a huge round hall from the Baths of Agrippa, the first great public baths of Rome. Marcus Agrippa was Augustus's oldest friend, the admiral who actually won the battle of Actium for him in 31 BC, and later his son-in-law. While Augustus collected titles, Agrippa built: aqueducts, porticoes, gardens, and the first temple on the site of the Pantheon, whose porch still carries his name, even though Hadrian rebuilt the whole thing more than a century later.

   To feed his baths, Agrippa built a whole new aqueduct, the Aqua Virgo, opened in 19 BC. Astonishingly, it still flows: it is the same water that pours out of the Trevi Fountain today. Around the baths he laid out gardens, an artificial lake called the Stagnum, and a canal that carried the water on to the Tiber. When he died in 12 BC, he left the baths to the Roman people, free of charge.

   The lake had a wilder afterlife. The historian Tacitus describes a party given for Nero on the Stagnum of Agrippa in 64 AD: a banquet on a great raft, towed by boats decorated with gold and ivory, and pavilions along the banks full of noble ladies... of whom Tacitus does not approve at all. Shortly afterwards, the Great Fire broke out and burned much of the city.

   Augustus liked to boast that he found Rome a city of brick and left it a city of marble. Stand in front of this battered wall and remember who did a great deal of the work... and that most of it now lies several metres below your shoes. Follow the lane east, along the back of the Pantheon, into a small square where an elephant is waiting for you.

5. 5. Bernini's Elephant & Galileo at the Minerva

   Piazza della Minerva, 00186 Roma RM, Italy

   Say hello to the most charming animal in Rome: a small marble elephant in a long saddle cloth, trunk curled back, carrying an Egyptian obelisk and watching you with a faintly mischievous eye. Romans nicknamed it the Pulcino della Minerva, the little chick of the Minerva.

   The obelisk is far older than its elephant. It was carved in Egypt for the pharaoh Apries in the 6th century BC and brought to Rome for the great sanctuary of Isis that once filled this neighbourhood. Here is the paradox: Augustus built his legend on defeating Cleopatra and Egypt, yet Egypt's gods conquered his Campus Martius anyway, with a temple full of obelisks, sphinxes and statues. Dominican friars dug this one up in their convent garden in 1665.

   Pope Alexander the Seventh asked Bernini to raise it, and Bernini designed the elephant, carved by his assistant Ercole Ferrata and unveiled in 1667. The story goes that a Dominican friar insisted no elephant could carry such a load on an empty belly, so a block of stone was put underneath, hidden by that oversized saddle cloth. Bernini, the legend says, took his revenge: walk around and see where the elephant's backside points... toward the friars' convent.

   That convent holds a darker memory. On 22 June 1633, in a hall of the Dominican convent of Santa Maria sopra Minerva, Galileo Galilei, sixty-nine years old, knelt before the cardinals of the Inquisition and abjured the idea that the Earth moves around the Sun. The famous muttered reply, and yet it moves, is almost certainly a later legend. He spent the rest of his life under house arrest.

   The church's name is a little archaeological joke: Santa Maria sopra Minerva means Saint Mary above Minerva, because medieval Romans believed it stood on a temple of the goddess. It is Rome's great Gothic church, with Michelangelo's Risen Christ inside and the body of Saint Catherine of Siena under the high altar. Beneath it all lie the foundations of older gods. Now walk east into Via del Piè di Marmo, the street of the marble foot, glance at the giant sandalled foot on its corner, and then turn north toward a row of colossal columns.

6. 6. Temple of Hadrian: A God Inside the Stock Exchange

   Piazza di Pietra, 00186 Roma RM, Italy

   Stand with your back to the cafés and take in the wall facing you: eleven enormous fluted marble columns, each around fifteen metres tall, scorched and pitted, with the windows of an office building peering out between them. It looks like a temple swallowed by a bank... and that is more or less what happened.

   This was the Temple of the Deified Hadrian, dedicated in 145 AD by his adopted son and successor, Antoninus Pius. Hadrian was the emperor-architect, the restless traveller who rebuilt the Pantheon a few streets away and left Agrippa's name on its porch. He died unloved by the Senate, which was reluctant to make him a god, and it took Antoninus's stubborn insistence before this temple could rise in its colonnaded square.

   The temple was decorated with reliefs of the provinces of the empire, each one shown as a woman in local dress, a kind of marble map of Roman power. Some of them survive in museums in Rome and Naples. The columns survived because they were useful: in the 1690s, under Pope Innocent the Twelfth, the architect Carlo Fontana and his son turned the ruin into the papal customs house for goods arriving by land.

   So merchants paid their duties among the columns of a god. Later the building housed Rome's stock exchange, and today it belongs to the Chamber of Commerce. Romans like to joke that the temple never really changed religion. Now look down at the foot of the columns: their base is partly exposed below today's paving, because the ancient piazza lies several metres beneath the modern one.

   Hadrian admired Augustus and copied him in more ways than one. He too built an enormous round mausoleum for his dynasty, across the river, the building we now call Castel Sant'Angelo. Keep that in mind for the end of this walk. Now take the short Via dei Bergamaschi north, and step out into a square dominated by another emperor's column.

7. 7. Column of Marcus Aurelius: The Philosopher's War

   Piazza Colonna, 00187 Roma RM, Italy

   In the middle of the square, a column of white marble rises about thirty metres, wrapped in a spiral of carved soldiers, with a bronze Saint Paul standing on top. The palace behind it, Palazzo Chigi, is the office of the Italian prime minister, so expect police, cameras and the occasional protest.

   The column honours Marcus Aurelius, the philosopher-emperor who wrote the Meditations, and who spent most of his last years not philosophising but fighting Germanic and Sarmatian tribes along the Danube. He died in 180, and the column was finished by around 193. It copies Trajan's Column near the Forum, but look closely and the mood is different: the figures are cut deeper, the faces are more dramatic, and the war is far crueller. Villages burn, prisoners are executed, women and children are dragged away.

   Somewhere on the spiral, if your eyes are good, is the famous Rain Miracle: a Roman army trapped and dying of thirst, saved by a sudden storm, shown as a huge winged rain god with water streaming from his arms and beard. Pagan writers credited the gods, or an Egyptian magician travelling with the army. Christian writers later insisted it was the prayers of Christian soldiers. Everyone wanted the credit for that cloud.

   In 1589 Pope Sixtus the Fifth had the column restored by Domenico Fontana and put Saint Paul on top, as a pair to Saint Peter on Trajan's Column. But the new inscription on the base got the emperor wrong: it dedicates the column to Antoninus Pius, Marcus Aurelius's adoptive father. For centuries the monument was known by the wrong name, and the mistake is still carved there in stone.

   The base you see was largely reworked in that restoration, and the ground the Romans walked on lies some way below today's paving. Every century since has added its layer of rubble and river mud, lifting the city a little higher over its emperors. Now walk a few steps west, along the side of the parliament building, into Piazza di Montecitorio, where a red granite obelisk once told the time for Augustus.

8. 8. Montecitorio Obelisk: The Hand of Augustus's Sundial

   Piazza di Montecitorio, 00186 Roma RM, Italy

   Face the front of Palazzo Montecitorio, home of the Italian Chamber of Deputies, a palace begun by Bernini, and in front of it a tall needle of red granite topped with a bronze globe. This obelisk was once the hand of the biggest clock Rome ever built.

   It was carved for the pharaoh Psamtik the Second in the 6th century BC and stood in Heliopolis, the city of the sun. Augustus brought it to Rome around 10 BC, together with the obelisk that now stands in Piazza del Popolo. The inscription he added to its base dedicates it to the Sun, as a gift, because Egypt had been brought under the power of the Roman people.

   He set it up on the Campus Martius, a short way north of here, as the pointer of a gigantic sundial, or more precisely a meridian: a long line of bronze set into travertine paving, marking the length of the noon shadow through the year. Pliny the Elder tells us a mathematician called Novius Facundus designed it and put a gilded ball on the tip, so the shadow would end in a sharp point. Then Pliny adds, a little smugly, that by his own day the readings had been wrong for some thirty years. Perhaps the ground had settled, perhaps the Tiber's floods had shifted the foundations.

   A famous theory by the German archaeologist Edmund Buchner claimed that on Augustus's birthday, 23 September, the shadow pointed straight toward the Altar of Peace. It is a beautiful idea, and still fiercely debated. What is certain is that Augustus wanted the sun and the calendar themselves to seem to turn around him.

   The obelisk fell, broke and vanished under houses. It was dug out in 1748, in pieces, and in 1792 Pope Pius the Sixth had it repaired, partly with granite taken from another ruined monument, the column of Antoninus Pius, and raised here, where Italy's laws are now debated. Walk north through Piazza del Parlamento and on to the calm square of San Lorenzo in Lucina, where part of the sundial itself still lies in the dark.

9. 9. San Lorenzo in Lucina: The Sundial Beneath the Cellars

   Via in Lucina 16A, 00186 Roma RM, Italy

   Settle into this calm square, with its cafés, its Romanesque bell tower and the low medieval portico of the basilica of San Lorenzo in Lucina, one of the oldest churches in Rome. It feels like a village. Under your feet, the Campus Martius of Augustus is still there, just out of reach.

   The church takes its name from Lucina, a Roman lady in whose house, tradition says, early Christians gathered. A church has stood here since late antiquity, and it was rebuilt in the 12th century, when the bell tower went up. Below the floor, archaeologists have found Roman apartment buildings of the 2nd century and an early Christian baptistery, layer upon layer.

   Inside, in a side chapel, is a piece of iron grill venerated as the gridiron on which Saint Lawrence was roasted in 258. Legend says he told his executioners, turn me over, this side is done... which is why he is the patron saint of cooks. The French painter Nicolas Poussin, who spent most of his life in Rome and died here in 1665, is buried in this church, with a monument paid for by the writer Chateaubriand.

   Now the hidden part. A few steps west, under a building on Via di Campo Marzio, archaeologists led by Edmund Buchner dug down around 1980 and, about six metres below the street, found a stretch of the great meridian: travertine slabs inlaid with bronze Greek letters naming signs of the zodiac, with notes such as the Etesian winds cease. It probably belongs to a later rebuilding of the sundial, but it is the real thing, the face of the clock whose hand you just saw, lying in the dark beneath a cellar.

   And one more ghost. The Altar of Peace itself originally stood just east of this square, beside the ancient Via Flaminia, today's Via del Corso, buried under the foundations of a Renaissance palace. Its fragments turned up over almost four centuries before anyone could free the whole thing. To see where it ended up, walk west along Via del Leone, turn right into Via di Ripetta, and look for a white pavilion of glass by the river.

10. 10. Ara Pacis: The Altar of Augustan Peace

    Lungotevere in Augusta, 00186 Roma RM, Italy

    Through the tall glass walls of this white modern pavilion, you can see a marble enclosure about the size of a small room, carved all over with garlands, animals and a procession of life-size figures. That is the Ara Pacis Augustae, the Altar of Augustan Peace, perhaps the most perfect political advertisement ever made.

    The Senate voted for it in 13 BC, when Augustus came home from campaigns in Spain and Gaul, and it was dedicated on 30 January, 9 BC, the birthday of his wife Livia. Inside the walls stood the altar where priests made sacrifices every year. Outside, the reliefs show Augustus, his priests and his whole family walking in procession, and the details are wonderfully human: a small boy tugging at a grown-up's toga, a woman who seems to raise a finger to hush the people chatting behind her.

    Over the centuries the altar sank under river silt and was built over. Pieces surfaced from 1568 onwards and scattered into collections in the Vatican, Florence and even Paris. In 1937 and 1938, for the two thousandth anniversary of Augustus's birth, engineers tunnelled under the palace on Via del Corso, froze the waterlogged ground with carbon dioxide so the building would not collapse, and pulled out the rest. Mussolini had it reassembled here, beside the emperor's tomb, in time for September 1938.

    Then came the glass. Richard Meier's pavilion, opened in 2006, was the first major modern building in Rome's historic centre since the fascist era, and Romans argued about it ferociously. One mayor even talked about tearing it down. It is still here, and the light inside is lovely, with the river glittering through the windows.

    On the long wall facing the mausoleum, look for an inscription in big Latin letters: the Res Gestae, Augustus's own account of everything he did, copied from a temple in Ankara, in modern Turkey, where the best version survived. He wrote it to be read at the door of his tomb. So let's go and read it there. Cross the square to the great round mound of brick and cypress trees: the man himself is waiting.

11. 11. Mausoleum of Augustus: The Emperor's Tomb

    Piazza Augusto Imperatore, 00186 Roma RM, Italy

    Walk to the railing and look down into the sunken garden: a vast round ruin of brick and concrete, ringed with cypresses, almost ninety metres across, sitting in a pit below the stern 1930s buildings of the square. This is the Mausoleum of Augustus, the largest circular tomb of the Roman world.

    Augustus began it remarkably early, around 28 BC, when he was about thirty-five and fresh from his victory over Antony and Cleopatra. In Alexandria he had just gazed on the embalmed body of Alexander the Great, and a man who builds his grave at thirty-five is not thinking about death. He is thinking about dynasty. The first to be laid here was his nephew and heir Marcellus, in 23 BC. Augustus followed in 14 AD, and the last emperor buried inside was Nerva, in 98.

    Then the tomb lived a dozen other lives. In the Middle Ages the Colonna family turned it into a fortress. Later it became a garden, then an open-air arena for bull games, fireworks and shows, and in the early 20th century a concert hall called the Augusteo, where Rome's great orchestra played. In 1936 Mussolini shut the concerts down, stripped the building back to its ancient core, and built this square around it as a stage for himself as the new Augustus.

    For decades after that, the ruin stood closed and overgrown, a home for weeds and stray cats in the middle of the city. After a long restoration it finally reopened to visitors in 2021. Inside its rings of corridors you get closer than anywhere else in Rome to the man who invented the Roman Empire... and who, remember, left his life story in bronze at its door.

    So here is the end of the walk, and the full circle. You began where Caesar was murdered, and you end at the tomb of the heir who turned that murder into an empire. In between you crossed his city: his rival's theatre, his friend's baths, his sundial, his altar of peace, all lying a few metres under the shopping streets. Every step today was on top of an emperor. Via del Corso, just to the east, will carry you back into the living city.