Natural disaster makes for great archaelogy. Pompeii and Herculaneum we owe to the fury of Vesuvius – and today Italy's Culture Ministry announced the dramatic discovery of the ruins of the tomb of the general who was the inspiration for the patrician-turned-vengeful gladiator played by Russell Crowe in the film Gladiator, fabulously well preserved thanks to a catastrophic flood.

The general in Gladiator, named Maximus Decimus Meridius by the film makers, was a favourite of the philosopher-emperor Marcus Aurelius in the late 2nd century AD and fought with him against the fearsome Germanic tribes who threatened to inundate Italy, beating them back and postponing the empire's decline and fall for another century or more.

All of this was also true of Marcus Nonius Macrinus, the man whose last resting place has now been identified. What is also true is that, while Marcus Aurelius is celebrated as a wise, prudent and benign emperor, his son and heir Commodus was a luxury-loving spendthrift who blew his father's careful legacy in a few years of riotous living and had a particular passion for gladiatorial shows.

Commodus was just the sort of emperor, in fact, who would likely have driven his old man's favoured generals up the wall with exasperation and contempt. Hence, in the film, the clash between the general and the new emperor, the destruction of the general's family, his exile as a slave and eventually triumphant – and highly improbable – return to Rome as a gladiator. All jolly good fun and completely fanciful, beginning with the patricidal murder of Marcus Aurelius by Commodus.

Concerning the true Marcus Nonius Macrinus, we know plenty about his military career – Daniela Rossi, the archeologist with Italy's Culture Ministry who reported this week's finding, says more than ten inscriptions have been found recording his triumphs, the fullest one to date being from Ephesus and in the Greek language – but tantalisingly little about what made him tick. He came from Brescia in northern Italy, where his was one of the most important families, he began his military career under Aurelius's predecessor Antoninus Pius, and fought valiantly and successfully against the Quadi and the Marcommani, the Germanic tribes which had crossed the Danube and were set on invading Italy.

Two years ago the remains of a great villa were discovered on the shores of Lake Garda, not far from the modern city of Brescia where the Fabia tribe to which his family belonged were the rulers. Here Macrinus lived with his wife Arria, who was from the Etruscan Arri tribe.

What is certain is that Macrinus was one of the most important figures of his age and an intimate friend of the emperor who was famous for his wise rule and his aphorisms, such as "Everything harmonises with me which is harmonious to thee, O Universe. Nothing to me is too early or too late, which is in due time for thee."

Doubtless he was one of the men on whom Aurelius most depended for the safety of the empire while he was ordering the construction of beautiful monuments and thinking great thoughts back in Rome. When Aurelius's brother Verus, with whom he had ruled jointly, died in battle, Macrinus was "chosen out of the closest friends", in the general's own words, to be a priest in the cult of the new Roman god Divus Verus, the deified spirit of the dead brother.

And when Macrinus died his son erected this magnificent tomb for him between the River Tiber and the Via Flaminia, the road leading north-east across the Appenines to the modern seaside resort of Rimini which Macrinus must have taken many times on his way to confront the Quadi and the Marcommani. Eight and a half kilometres from the city walls, it was in an area where his Fabia tribe had become important landowners.

Professor Rossi calls the find "the most important ancient Roman monument to come to light in the suburbs of Rome for many years," and she and her ten colleagues in the dig are now working against the clock to find what else is down there, stuck in the ancient mud which settled over the tomb once the flood had done its devastating work.

The site belongs to Gruppo Bonifaci, a Roman construction company, which has sponsored the dig and promised funds for a museum on the site to house the findings when everything has been recovered. But because of the site's commercial value to the firm – they plan to build housing on it - the archeologists have limited time to retrieve what can be retrieved, "perhaps until Christmas," says Professor Rossi.

The work is arduous because the ancient site of the tomb was seven metres below the present ground level. It was built at a depression in the landscape, another reason why in the long term it was a poor place to build anything, being vulnerable to the moods of the river nearby. Around 1500 Rome's rulers reached the inevitable conclusion and moved the Via Flaminia to higher ground further west where it would be safe from further flooding.

Today, as it has been unearthed over recent months by the archeolgists, the tomb looks much as it must have done when the Tiber's flash flood wreaked havoc on it, smashing walls and columns and pediments and caking the resulting mess in a coat of lime

"The tomb was destroyed by the river, perhaps by a sudden flood," said Professor Rossi. "We have only just begun to find how much is down there, so it is too early to say what form the tomb took, whether it was a single structure or two or several: much of it remains buried in mud; perhaps we will also find the sarcophagus. It's also too early to say how big it is, but it appears there was a row of columns at least 15 metres long, so it was quite huge."

When and how did Marcus Nonius Macrinus die? "We really don't know," admits Professor Rossi, "but if we succeed in finding the other two parts of the broken inscription, perhaps we will find out."