In paintings and sculptures from the last years of his life, Charles Darwin gives the impression of a man deeply wishing he could be somewhere else. At the National Portrait Gallery in London, he keeps his rumpled hat clutched in one hand, ready to bolt for the door. At the Natural History Museum, he has his coat folded across his lap, as if yearning to shed the burden of fame and slip quietly into oblivion. On the £10 note, his eyes are haunted beneath a vast furrowed brow, and there’s dismay behind that biblical white beard.

This image of Darwin is everywhere, and that seemed to me, on a recent trip to London, to be a pity. Even the founding father of evolutionary theory was not born a gloomy old man. I began to wonder if it might be possible to walk Darwin’s London and get a sense of him as a young man caught up in the fray. The landmarks of his life turned out to be all around. One day, for instance, I ducked into the Burlington Arcade—a handsome 1819 predecessor of the enclosed luxury shopping mall, where the bon ton of Darwin’s day shopped—and then, via another arcade, out onto Albemarle Street. To the right was the Royal Institution, where Darwin attended lectures. Brown’s Hotel, where a pro-Darwin group called the X Club used to meet in the 1860s, stood in mid-block. And though Darwin’s publishing company was sold off a few years ago to a conglomerate, the seventh generation of John Murrays still presides over the company’s old house just down the street. Murray told me he was already being inundated with visitors anticipating next year’s big anniversaries of Darwin’s birth (1809) and of the publication of his book

London has of course also changed. I went to visit 36 Great Marlborough Street, where Darwin was living in a bachelor flat when he got his first tentative inkling of natural selection, in September 1838, and I found the site occupied by a fast-food joint (slogan: “Scream if you want it faster”). I had better luck just below Trafalgar Square, where the Old Admiralty Building stands intact, screened off behind a handsome neoclassical colonnade from the broad avenue of government buildings called Whitehall. The modest U-shaped brick structure within served for centuries as headquarters of the Royal Navy and home ground to such storied mariners as Cook, Bligh, and Nelson. In September 1831, the 22-year-old Darwin came here for his first meeting with Captain Robert FitzRoy, who was seeking a gentleman naturalist to accompany him on a long expedition on H.M.S. Beagle.

The meeting went well: “Gloria in excelsis is the most moderate beginning I can think of,” Darwin wrote later that day. He was so eager to get started that he took lodgings around the corner on Spring Gardens, practically tucking himself in at night under the Admiralty’s left earlobe.