I first visited Lahore in 1995, illegally. I was attending a conference in Islamabad, and had a visa for that city alone. But I was determined to get to Lahore. I had grown up in a town in north India inundated with refugees from Pakistan’s Punjab. The fathers of my friends had all been educated in Lahore, and spoke in elegiac tones about its colleges, parks, theatres and shops. A book they passed lovingly from hand to hand was Pran Neville’s Lahore: A Sentimental Journey, an account of a sensuous and even sybaritic city, whose residents – at least in this telling – were preoccupied with the pleasures of clothes, food, music and sex.

Speaking of the 1930s, Neville wrote that “Lahore was famous for its sexologists, mostly [Hindu] vaids and [Muslim] hakims. They promised sexual prowess to all those who could afford their expensive formulations, which had ingredients like gold, silver, pearls and rare herbs.”

Neville’s memories were emblematic. Lahore is the Salonica of the east, a multicultural city in living memory that is now dominated by people of a single faith. Named after Luv, a son of the mythical God-King Ram, Lahore was governed by Hindus before coming under a succession of Muslim rulers.

The forts and mosques that are the city’s pride were built by the great Mughal emperors Akbar, Jehangir and Aurangzeb. When their empire collapsed under the weight of its contradictions, Lahore became the capital of a Sikh kingdom, established by the one-eyed warrior Ranjit Singh. The Sikhs were in turn replaced by the British, who made the city the capital of the province of the Punjab. Then, in 1947, came independence, partition, and the exodus of Sikhs and Hindus from Lahore into India.

On that first trip, my companion was a Bangladeshi who had studied in Lahore’s Forman Christian College when his land was still part of Pakistan. I met him at the Islamabad conference and now he took me through Lahore’s main sights – the magnificent, white-domed Badshahi (“Emperor’s”) Mosque, built by Aurangzeb; a medieval watchtower on an island in the river Ravi; the mazaar, or resting place, of the mystic saint Datta Ganj Baksh; and the mausoleum of the modern poet Allama Iqbal.

Late last year I was invited to a meeting of historians in Lahore and received my visa on November 24. Two days later, terrorists based in Pakistan attacked Mumbai. India’s foreign ministry issued an advisory warning Indian citizens not to travel to Pakistan. My mother, for whom this 50-year-old is, well, still a boy, urged me to heed the advisory. An aunt added that I had no business in an “enemy country”. Their sentiments and reservations were vetoed by my teenage daughter, who insisted that I must go, if only to demonstrate that “not all of us hate all of them”.

In the 1640s Portuguese priest Fra Sebastian Manrique described Lahore as a “handsome and well-ordered city with large waterways and pavilions of various colours. The abundance of the provisions and cleanliness of the streets surprised me much; also the justness and rectitude of the people towards each other…”

Then, and for three centuries to come, Lahore was a city in which many Muslims resided and some Muslims ruled. After partition, it became a Muslim city, denuded of the Hindus and the Sikhs who had also once helped to define it. Even so, it remains the most broad-minded of all the towns in Pakistan.

Unlike in Quetta and Peshawar, Islamic fundamentalists do not dictate how people should dress or otherwise comport themselves. Unlike Karachi, it is not crippled by sectarian violence. It retains a rich musical tradition, associated with such singers as the burly and full-throated qawwal, the late Nusrat Fateh Ali Khan. It is the centre of modern art and theatre in Pakistan. And the country’s best (and bravest) newspaper is published from Lahore.

One night, I was taken to dine at Kutu’s, a restaurant on the top floor of an ancient haveli overlooking the Badshahi Mosque. The conversation was sombre, focusing on the fears of the Lahore middle class in this time of national instability and transition.

The Islam on display in Lahore is pluralistic, mystical and suffused with song and poetry. How long would it be able to withstand the austere and puritanical strain now sweeping across Pakistan?

A second threat comes from the men in uniform. On the edge of the Mall Road is a massive shopping complex owned by the army, replete with a giant wheel and bright signs for KFC, McDonald’s and other foreign brands. The complex carries the splendidly Orwellian name of Fortress Stadium. The generals had used their years in power to acquire the best real estate.

The intelligentsia of Lahore also worry about being abandoned by the world. As an Indian, I would probably have been welcome in any case – but the fact that I had come when advised not to made my hosts even more expansive. There were only 18 passengers on my flight, and the stewards fell over themselves to attend on us. So did the staff in my hotel: when the time came for me to depart, I found they had lined up in a sort of guard of honour. The manager invited me to come back, and to bring friends next time. I asked them to come to my homeland. One person said he had been to India. When I asked whether it was to call on relatives, he answered (in Urdu) that no, he had gone to see friends, a Sikh family living in Delhi.

I was moved by this attempt to reclaim a fast-disappearing past. The young man knew his city had once been a seat of Sikh culture and Hindu learning. He also knew that many foreigners now thought of his country as in danger of being overrun by Islamic fundamentalists. And so he wished to tell me that among his own friends was an Indian who was not a Muslim.

Ramachandra Guha, author of ‘India after Gandhi’, will be speaking at the London Book Fair on April 22