No one can nail a painting like Robert Hughes. His seminal book The Shock of the New (1980) cracked open 20th-century art in prose so exuberant it threatened to out-dazzle the works themselves. His subsequent books, most recently a biography, Goya (2004), and a memoir, Things I Didn’t Know (2006), have maintained the Australian-born critic’s reputation. However, confronted with the story of a 2,500-year-old city that he describes as “sublime and inordinately complicated”, he flounders.

Frustratingly, the prologue of Rome whets the appetite for a tour de force. Hughes plucks two civic statues – that of the heretic philosopher Giordano Bruno executed by the Inquisition and the ancient bronze of emperor Marcus Aurelius on horseback – to illustrate a city where violence and high culture are inextricably entwined. Rome’s uniquely sensual allure is conjured with images of the “swollen purple truncheons of aubergines” in the market; and – courtesy of Octavio Paz – a fountain as a “willow of crystal, a poplar of water”.

However, problems arise when he attempts more scholarly analysis. The rambling quality of the account of ancient Rome leaves the reader pining for the more specialised narratives from which it has clearly been strung together.

A gripping analysis of the Pantheon illuminates the Roman invention of concrete, which allowed for the construction of domes where the Greeks were confined to building in straight lines. But why does Hughes shy away from the art criticism that is his forte? Regarding the frescoes that adorned the walls of Pompeii, Hughes states that: “There is no sign that Roman walls in Augustus’ time had anything comparable.” This is not true: the remains of two ancient villas discovered in Rome during the 19th century yielded exquisite frescoes which suggest that mural painting was widespread in patrician Roman residences.

Had he acknowledged the existence of Roman frescoes – which drew on Greek style but also innovated – Hughes would have had to modify his belief that all Roman art sprang from “a general culture of intense imitation” of Greece. Even when this was true, for example in sculpture, those Hellenic origins are revealing of Rome’s cultural fantasies.

No period left its imprint on Rome more decisively than the Counter-Reformation. Here, a nuanced account captures the era’s creative zeal and the anxiety that fuelled it. There is a riveting narrative of the operation ordered by the “manic-impressive pontiff” Pope Sixtus V to move the 361-tonne Egyptian obelisk from the back of St Peter’s to the front. Equally evocative is the description of the baldachino erected by Bernini over St Peter’s tomb. The bronze monument is “a huge, exuberant declaration of the belief that St Peter, Christ’s Vicar on Earth, lay buried here and nowhere else”.

The final chapters take Italy through unification up to the present day. A thoughtful exploration of artists and architects’ rapport with Fascism, an issue skirted by most Italian art historians, includes a welcome critique of Mario Sironi, a forgotten but extremely talented painter whose distasteful political beliefs in no way undermined the power of his “dark, harsh landscapes”.

Hughes describes late 20th-century Rome as “irksome, frustrating and contradictory”. Yet he buries that complex reality in a blizzard of contemptuous clichés. For example, Arte Povera, which actually threw down a serious conceptual challenge to Pop Art, is dismissed for producing “objects of modest interest”. Instead, approval is reserved for La Dolce Vita, Federico Fellini’s film.

Hughes is right to target Silvio Berlusconi as a “man with no cultural interests” but to describe most Italians as “artistic illiterates” is to insult the large percentage who repeatedly vote against their low-brow leader. Most telling is the absence of any mention of Maxxi, which opened in Rome last year. Designed by Zaha Hadid, the €150m building is the first state-sponsored contemporary art museum in Italy. To ignore it reveals more about Hughes’s own declining energy than that of the city he once loved.

Rome, by Robert Hughes, Weidenfeld & Nicolson, RRP£25, 576 pages

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