First published in 1974 – Barack Obama read it aged 22, and was “mesmerised” – The Power Broker was released in the UK for the first time this year. But its themes are too timeless to seem dated. Like the multivolume biography of Lyndon Johnson for which Caro is best known, you might call The Power Broker “unputdownable” – except that, at 1,300 pages, putting it down occasionally is the only way to avoid sore muscles.

You needn’t care especially about New York to be awed by the changes Moses wrought there: during a 44-year reign, he built nearly 700 miles of road, including the giant highways that snake out of the city into Long Island and upstate New York; 20,000 acres of parkland and public beaches, plus 658 playgrounds; seven new bridges; the UN headquarters, the Central Park zoo and the Lincoln Center arts complex, racking up expenditures of $27bn, dwarfing any previous run of construction in US history. “In the 20th century,” wrote Lewis Mumford, “the influence of Robert Moses on the cities of America was greater than that of any other person.” Around 500,000 people, who happened to find themselves in the way of Moses’s vision, were evicted from their homes. Did he drag New York into the modern age, forcing through much-needed public works and eradicating intolerable slums, against opposition from corrupt politicians and landowners? Or did he nearly destroy the city, subjugating its human inhabitants to the sovereignty of the car?

Caro, a former newspaper reporter, doesn’t pretend to be neutral: note the book’s subtitle. In Caro’s telling, Moses started out an idealist, inspired by his mother, a pillar of the New York German-Jewish community, whose zeal for helping the less fortunate was matched by the certainty that she knew, without asking them, what they needed. But Robert soon found that ruthless pragmatism got more things done. One early incident is emblematic: deep in the boring sub-clauses of a New York State bill, he buried a radical redefinition of the word “appropriation” – so that the law, once passed, gave the Long Island State Park Commission, which Moses controlled, the power “to write its own laws, hire its own policemen to enforce them and prosecutors to prosecute them”.