Caroline, my wife, is feeling unwell. It seems that the city is not agreeing with her. We are sitting on a bench in the Lustgarten, looking across the road to the Palace of the Republic. I had hoped we would be able to go in, but the building is closed, a rusting, derelict hulk deemed unsafe due to structural flaws, asbestos, or — it seems possible — more symbolic dangers.

The palace was the nerve centre of the German Democratic Republic, a paranoid state obsessed with the duplicity of its own people. It presents four walls of oily, bronzed glass — intended, it seems, to conceal everything that went on inside it, but which now conceal nothing, I imagine, except gutted offices, dim and draughty corridors. Instead, reflected in the glass is a corrupted, cubist vision of the city around it — shards of the cathedral’s copper-green dome, Karl-Liebknecht-Strasse, the Spree river and roiling sky.

Now some want it knocked down, while others would have it preserved as a reminder of the crimes committed inside. I have been explaining this to my wife, but now she is lying down on the grass with her eyes closed. Her face is flushed. She says she feels dizzy.

“It’s so depressing here,” says Caroline, not opening her eyes. “So grey, so much concrete, so many terrible things. I feel like I can’t breathe.”

The city is much as I had imagined it: cold and grand, claustrophobic with history. The architecture is monumental, designed to intimidate. In the great plazas and boulevards I find it hard not to think of grainy black-and-white film, thousands marching, crowds raked with searchlights.

As we have criss-crossed the city under my direction, my wife has proved a reluctant tourist. She seems oppressed by everything — the run-down buildings near our hotel in the old east of the city, the incomprehensible graffiti that cover them, the surprising quietness of the streets. She complains frequently of tiredness.

We have argued. She has decided that my interest in the city is unsavoury, voyeuristic.

“A strange thing,” I say, shutting the guidebook and sitting down next to her on the damp grass. “Something that strikes you when you read about it is that throughout the war, even very late on when many Germans must have known it was lost, life just seemed to go on as usual. People had dinner parties. They saw friends, went to parks, bars, the theatre. They even went on holiday. Everything was heading towards this disaster, this catastrophe, really. Thousands were dying all over Europe, but, amid the chaos, in some ways life just went on as usual.”

Caroline does not speak. She opens her eyes briefly to check my expression. Lately she has become suspicious of everything I say. She thinks everything is innuendo, an accusation or a trap. It is spotting with rain. “Ready to go on?” I say.

“Please,” she says. “I have to go back to the hotel.”

Two months ago I discovered that my wife was having an affair. She was so careless in her deceptions, so reckless in her choice of lover — a friend of ours — that I believe she wanted me to catch her, that she wished to punish me and make me suffer. There were plenty of clues, and anyway I was not so surprised.

I let the affair continue for several weeks — keeping track of her movements, imagining their meetings. In the end it played out like melo-drama: the husband arriving home unexpectedly from work, the opening of the bedroom door, the wife and her lover momentarily oblivious of their discovery. Perhaps it sounds strange, but this is what I had wanted to see — for her to know I had seen — so that there could be no excusing or reducing it, no pretending it was something other than this, no softening with words or regret.

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