THEATRE:Friends, Romans and cross-dressers

FROM THE Amphitheatre of Delphi to his father's graveyard in Leeds, Tony Harrison has specialised in releasing the genius loci; but he has never found a better place than the Roman arena at Carnuntum - midway between Vienna and the Slovak border - for dramatising the paradoxes of civilisation.

Built as a military outpost on the barbarian frontier, Carnuntum was a Roman Chicago where the meat turned into money - where wild-beast shows, symbolising foreign conquest, persuaded the taxpayers to invest in the Empire. From here, Marcus Aurelius made war on the Marcomanni and wrote his stoic Meditations. Here, too, his 11-year-old son, Commodus, first witnessed the bloody entertainments that became his ruling passion. Such is the genetic conundrum of Carnuntum: the philosopher father and the bestial son. In the words of another poet "This thing of darkness I acknowledge mine". Remember, too, that this is Germanic territory, the home, as Kurt Tucholsky said, of both Dichter und Denker (poet and thinker) and of Richter und Henker (judge and hangman).

Harrison's The Kaisers of Carnuntum represents the theatrical exorcism of a place that last saw action 1,700 years ago as a slaughterhouse. The play itself is a gladiatorial combat between Greek fiction and Roman fact, and, as befits the event, it is spectacular. Within the arena Harrison's designer, Jocelyn Herbert, has built a scaffolding arena of her own surmounted by four towers. As you look down you see a floor map of the Empire converging on a model of the Coliseum on the central blood sump that drains into the Danube. The scaffold's inner walls display painted enlargements of animal-combat mosaics, concealing real lions and tigers caged and roaring under the audience's feet. As you look up, you see the white-suited figure of Marcus singing a philosophic prelude on the transience of empire in an unearthly counter-tenor: "Rome had to be a Hercules / to turn barbarians like these / into cultivated Viennese." At which point, Marcus and his string quartet are drowned by gunfire and searchlights, and the Roman Hercules appears in the explosive person of Barrie Rutter's Commodus.

This is a double shock, as it also plunges the show into brutal comedy. Returning to reclaim his territory, the Emperor-gladiator swaggers round the arena as a lager-lout demon king, bawling for drink in pantomime couplets. At once earthy and learned, this style is a trade-mark of Harrison's stage writing; but it might have been invented for Commodus - a thug who knows all about Sophocles and is not impressed. Undercutting every threat with a gag, he first comes over as a clown ogre; then, in the second shock of the night, he clubs a sign-writer to death, thus reconsecrating the space to bloodshed.

Harrison's original title was Carnuntum Cantata, which is a fair description of a piece that depends on martial and choral music (Richard Blackford), and generally excludes dialogue in favour of rituals and rhetorical solos. But a clear central action (not previously Harrison's strongest point) emerges in Commodus's promise to uncage the animals for a killing orgy: for him, this is at once a means of converting the modern public, provoking an encounter with his father, and defeating Orpheus (exquisitely played by Jaro Frank, the keeper of a local wild-life park). The moment of carnage is teasingly delayed: by a ritual transformation of slaughtered meat into the bodies of barbarian children; and by the thrilling intervention of Commodus's mother, Faustina (Sian Thomas), who delivers a maternal elegy for tyrants throughout history. Poetically, this wonderful speech is the climax of the event; but you are still left wondering how Commodus - now stripped for combat in sex-shop underwear (Hercules, he reminds us, was a cross-dresser) - will fulfil his pledge actually to let loose "the most savage beast". Enter Orpheus who runs him through with a cello spike, impaling the art-hating hero on a classical peripeteia. Commodus himself is that beast. Harrison himself then makes a modest entrance to announce the triumph of art - only to flee in panic, scattering his papers, when the bleeding protagonist arises from the Coliseum with a threatening roar. The execution of one tyrant gives birth to the next. The production ran for only two nights and will probably never be seen again, but its message lives on.

It has certainly been echoing around the past week's London shows. In Terry Johnson's revival of his 1982 piece, Insignificance, the Aurelian figure of Einstein (Alun Armstrong) does battle with a McCarthyite Commodus while debating relativity with Marilyn Monroe (Frances Barber). And Jupiter in Kleist's Amphitryon expresses his thanks to the cuckolded protagonist by granting him the parenthood of Hercules. In a packed week, I can do no more than recommend these shows; plus the London transfer of David Edgar's magnificent Pentecost.

'Insignificance': Donmar Warehouse, WC2, 0171 369 1732. 'Amphitryon': Gate, W11, 0171 229 0706. 'Pentecost': Young Vic, SE1, 0171 928 6363.