I know that somewhere round here lies the very spot where the landlord of Number 11 beckoned Hunger's hero across to the door, and motioned for him to be quiet before inviting him to peer through the keyhole. The hero can make out two figures on the bed. His landlord's wife's naked legs show stark white against the dark quilt; she is heavily pregnant. The new tenant, a seaman, is lying between them.
Her husband is trying to stifle his laughter at the sight of her old father sitting on the settee on the other side of the room. Unable to look away because of his paralysis, he is forced to witness the event.
Risque even now, this scene had a dramatic effect on conservative Oslo at the turn of the century. Nobody had written like that before. It is likely that this was a real episode in Hamsun's life. At the end of the Second World War the ageing writer was tried as a Nazi sympathiser. For that reason, few people read his books now, and yet Hunger was to change the course of Western literature.
From the station it is possible to pick the steps of Hamsun's hero as he stalks Ylayli, the imaginary name he gives the young woman he becomes obsessed with. He follows her up and down Karl Johans Gate from the royal palace at its opposite end. The first half of the street is pedestrianised now. Above the jewellers, the shoe shops and restaurants, the buildings have altered little in the last 100 years. In the Grand Cafe, had he looked through the large windows, he might have caught sight of Henrik Ibsen quaffing and dining.
Here the pavements widen into a boulevard lined with trees. Running down the centre there is a garden with open-air cafes. The people of Oslo sit here on summer evenings drinking beer and gossiping as they watch the promenade of the fashionable young.
Ibsen's plays are still performed at the National Theatre at the far end of the boulevard. Across the road is another of the dramatist's haunts, Theatre Cafi. Its Art Nouveau interior is as it was in his day - a small orchestra plays from the gallery each evening. The menu is largely Norwegian, luscious reindeer steaks a speciality.
Ylayli walks on with her friend, dogged by Hunger's hero. Just before the university they turn right and walk up Universitet gate and past the National Gallery. Far fewer people know of Edvard Munch than know of his painting, The Scream, which hangs inside. After the Mona Lisa, it is the most famous painting in the world. No other picture so captures the soul of the 20th century. Yet it was painted in 1893, three years after Hunger was published.
Aware that they are being pursued, Ylayli and her companion hurry along Universitet gate and on to St Olafs Plass. Number 2 is now a Salvation Army charity shop in a Sixties block. In the building that stood here lived an Ida Charlotte Clementine Wedel-Jarlsberg. She was the inspiration for Ylayli and it is that surname Hamsun's hero uses when he spends a night in the city gaol. I walk along to the Kunst Industriet Museet. Inside it reminds me of the V&A on a much smaller scale.
Wandering aimlessly in the streets behind the museum, I stumble across All Saviours' graveyard where the hero sat on a bench going slowly mad from want of food. Hamsun's experiences of hunger were not uncommon in the 19th century. Like hordes of other Europeans, thousands of Norwegians sailed for America to escape the grinding poverty. Hamsun went there himself.
Both Munch and Ibsen are buried in the graveyard along with many of Norway's writers, poets and artists. But Hamsun is not. Though he haunted it in life, in death he was deprived of the opportunity.
To the north are a few wooden houses. They give another insight into how much of old Christiania - as Oslo was called - used to be. Until recently nobody wanted to live in them and they begin to fall into disrepair, but now the few houses that are not inhabited have become studios and offices. It's almost trendy. One doubts that that was the case when Munch grew up in the area. His father was a doctor with a meagre practice. His mother died of tuberculosis when he was five. His sister, Sophie, followed nine years later. These two events are said to have created his hypochondria and obsession with both sickness and death.
But to see Munch and Hamsun purely as angst-ridden souls is to misunderstand the Scandinavian psyche. Hamsun can be outrageously funny; Munch was a hedonist who spent his evenings downing bottles of wine and enjoying whores, only to spend his days deep in alcoholic remorse.
The Munch Museum lies to north of the old town. I took the underground to Toyen station. Surrounded by a few trees, the museum lies a short stroll away. The full breadth of Munch's work hits me in the face like a blast from a furnace. It's the sheer scale of some of the paintings as much as anything, as big as houses. Their colours are the light of Norway itself, sharp and clear primaries. I come away my head a buzz of stark Nordic imagery.
From the wharves in front of the town hall - where Hamsun's hero, escaping debt, takes a ship bound for England - I look up to the blue-green horseshoe that is Oslo and its surrounding hills gradually descending into the fjord, and suddenly something makes sense. At the moment when the setting sun transforms a myriad glass panes into glinting sheets of gold, I see what Hamsun must have seen. It's in the last few lines. I never quite know what he was alluding to. He's swabbing the deck of the ship when he looks up to bid farewell to Christiania. I knew there was more to it; "the windows of the houses shine brightly back at him".
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