It was on the 15th day of the Egyptian revolution that I first encountered Ahdaf Soueif in Tahrir Square. She wore big round sunglasses that swallowed her face, and a dark scarf covered her head and fell over her shoulders. It would have been easy to dismiss her as just another spirited revolutionary, but a flock of fellow protesters grew around her, and followed her, and stuck.

"Write, please write," one man urged her. "I live in one room, I have six children. Please, bring a TV crew and film my home. I am willing to work, willing to earn an honest wage, willing to put in long hours."

"I have documents, proof of what they've done, the government," another began.

I approached her myself when I too, realised who she was; she spoke first of women and their extraordinary role in the revolt, and then looked me in the eye and said that she had dreamt of this. "I had a vision of revolution. It happens in Tahrir  Liberation Square."

Whether Soueif actually dreamt of the revolution in its current form  as many have themselves claimed since  or whether she simply yearned more broadly for liberation, I never did find out. But to read her new book is to understand that the novelist and commentator long sought if not a liberation, or even reconciliation, then at least a gentle closure and a means of addressing her longing for the city of her youth.

Much of Soueif's fiction over the years has felt burdened by a melancholy for Cairo, which became her second home after marriage took her to London in 1984, and she begins this new book with an almost chilling admission of such: "Many years ago I signed a contract to write a book about Cairo; my Cairo. But the years passed, and I could not write it. When I tried it read like an elegy; and I would not write an elegy for my city." For anyone who has lived the decline of Cairo over the years and under the increasingly despotic and corrupt Mubarak regime, the sense of loss, of the irrevocable, had become as much a part of the urban fabric of place as it had become a state of mind. Cairo has felt heavy. "Streets were dug up and left unpaved. Sidewalks vanished. Prime and historic locations became car parks. Streetlights dimmed. Nothing was maintained or mended. Old houses were torn down and monstrous towers built in their place  The day the Cairo Tower lost its discreet white uplighting and was caught in a net of flashing coloured dots I cried."

In these details of her Cairo, which are interspersed throughout her record of the revolution, Ahdaf captures a cultural memory that is shared by many. Equally, she documents the events and predicaments that both troubled her and also came eventually to make January 25: "A quarter of a million children lived on the streets and some people set up shelters for them and some filmed them and some stole their kidneys and corneas. Police officers ran protection and drug rackets. People regularly fell out of windows during questioning or had heart attacks in police custody  The top judges of the country stood for two hours in silence in the street outside the Judges' Club with their sashes and ribbons and medals on their chests. We knew then that judgment would surely come."

In this book, which stands much more as a chronicle of that judgment, or revolution, than anything else  a personal testimony of time and place and experience  we are introduced to a writer who seems lighter, freer, less conscious of the weight of her prose and the story she has set to tell.

There are many records of the Egyptian revolution, but Cairo takes us on a more intimate journey; one that goes far beyond the 18 days of Tahrir Square, to the places in her memory: her aunt's flat in Lazoghli, now the centre of the battle with state security; Maspero, where she had her first job, and now the mouthpiece of Mubarak's regime; and the many rooms and views and places that bring back memories of her mother ("I cannot tell you how many people in the Square have said to me, can you imagine if your mother were alive today? How she would have enjoyed this?"). We gain access that only a local  and a well-connected one  can provide, and we get an insight to a world that only a member of the Soueif family could offer: Soueif's sister, brother-in-law, nieces and nephew are all seasoned and prominent activists, and in the course of the narrative we hear of their beatings and arrests and disappearances and detentions. She offers glimpses of past and future as well as present. Of 28 January 2011, she writes: "Through the night of this Friday that will come to be known as the Day of Wrath, the regime killed hundreds of Egypt's young  Families will spend months of heartbreak finding out and trying to prove how they were killed. Brave doctors and lawyers will speak up for them. The Dakhleyya (interior ministry) will continue  as I write  to deny responsibility".

Although Soueif admits to worrying about "writing the revolution" when she actually needed to be part of the revolt, she seems to have successfully done both. Her voice in Cairo is different to that in her two novels and several collections of stories and commentaries; it is a voice that speaks of her own story but also speaks for thousands, perhaps even millions, of other Cairenes.

Soueif writes that this book, the one she signed on to write many years ago, was never written because "it hurt too much". Yet I find myself wondering if this really is her definitive Cairo book, or if there is yet another one, a deeper one, a more nuanced one  the book that she had been struggling with, and that she alludes to, and that lies somewhere on a hard-drive or in a drawer unfinished. I find myself still wanting to know more about this lyrical Cairo of hers of which we catch only fleeting and compelling glimpses.

Yasmine El Rashidi's The Battle for Cairo is published by NYRB.