COMMENT: Friday Book - European history through the eyes of the Tsar's lover

The Pilgrim Princess: a Life of Princess Zinaida Volkonsky by Maria Fairweather, (Constable, pounds 25)

VILLA VOLKONSKY in Rome has been the residence of the British Ambassador to Italy since the end of the war. Originally it belonged to Zinaida Volkonsky, a wealthy Russian princess who in 1830 bought a large estate on the edge of Rome. Standing on high ground, it commanded a magnificent view over the Campagna and the Sabine and Alban hills. Today it has been absorbed by urban expansion and the view has gone, but the lush garden, strewn with ancient statuary, is still enchanting.

Who was Zinaida Volkonsky? Maria Fairweather, herself half Russian, arrived at the villa in Rome in 1992 on her husband's posting as British Ambassador and began to find out. Her research took her to archives and libraries in Russia, Germany, Austria, France and the nearby Vatican. The result is this enthralling historical biography. Her book brings to life one of the most cataclysmic eras of European history through the story of a beautiful woman who started out as a fairy-tale princess and died a saint.

Zinaida was born into the highest aristocracy in 1789. Her father was Tsar Alexander I's Chamberlain, and his ambassador to various European courts. Zinaida's early life coincided with the Napoleonic Wars; at 17, she married Prince Nikita Volkonsky, an aide-de-camp to the Tsar, and became lady-in-waiting to the Dowager Empress. Beautiful and spirited, she spoke several languages, wrote poetry and prose in French, played the piano and harp, and "sang contralto like an angel", as Stendhal wrote.

Soon she was the "loveliest ornament of my court", the Tsar wrote to her. They fell deeply in love; when their affair ended, she remained his friend and life-long confidante. She travelled in his suite to the Congress of Vienna; impressed Wellington and Talleyrand with her beauty and intelligence; inspired poets and artists with her warmth and grace. She became one of Europe's most famous women.

Maria Fairweather charts Zinaida's life and loves in the context of Europe's turbulent history and peppers her tale with telling anecdotes and amusing vignettes. In Vienna, while emperors and statesmen "spent their days redrawing the map of Europe, the evenings and nights were wholly given over to pleasure and frivolity". Metternich gave a ball for 1,800 people, lit with 10,000 candles glinting against fabulous jewels. Beethoven played for Zinaida at Prince Razumovsky's salon.

In the 1820s, Zinaida's salon became the hub of intellectual life in Russia. Poets, writers, musicians and artists - including Pushkin, Turgenev, Belinsky - flocked to her soirees in Moscow and St Petersburg. When, in 1830, she settled in Rome, her salon became the rendezvous of European writers and artists: Donizetti and Rossini, Walter Scott and Stendhal. She wrote and published poetry and prose, and composed operas and cantatas.

Maria Fairweather writes with a fluency and charm worthy of her subject. Anthologies of Zinaida's writing are still extant in French, and by quoting from them as well as from poems, letters and diaries, she conjures up the atmosphere of Zinaida's milieu. Her description of lavish receptions and balls, with the enchanting hostess the soul of the party, bring to mind scenes from War and Peace.

Yet Zinaida was more than a great beauty and minor artist: she was genuinely kind and generous, pulling strings with Tsar, Pope and politicians on behalf of those in trouble or need. She converted to Catholicism, and over time developed mystical aspirations. She became dotty, began to have visions, and drove Gogol crazy with her proselytising.

Gradually Zinaida withdrew from the world and became a tertiary of the Franciscan Order, giving her life entirely to "poverty and prayer". Beggars queued at her door, and "she gave away not only alms but also her own clothes". One winter day, she saw a beggar woman shivering in the cold. She took off her own warm petticoat and gave it to her. Frozen through when she reached home, she caught a cold and died shortly after, aged 72. The poor of Rome formed a small cortege and followed her to her resting place in the Church of Sts Vincenzo and Anastasio. Her friends the Pope and his cardinals never got round to beatifying her, but the poor and dispossessed she had lovingly tended did: they called her Beata, Blessed. This is a wonderful book.