John Kelleher takes the London Underground to visit the Mandir. From Neasden Underground station it's easy to recognise the twin-domed towers rising in the distance above the tangle of streets beside the North Circular Road as a place of worship. The towers crown Wembley Stadium and enshrine a turf sacred to a very contemporary faith. Nearby is a tower block that helps pilgrims pinpoint another modern mecca, the gargantuan furnishing store, IKEA.
But in recent years a much older faith has brought crowds surging through these north London streets. They come from across London and further afield to the Swaminarayan Hindu Mandir. Their devotion has created the nearest thing to a medieval cathedral built in Britain for centuries.
The first sight of the Mandir takes your breath away. Behind modest redbrick walls rises an astonishing cluster of white marble spires and domes topped with gold pinnacles and pennants that whip in the breeze. Its walls of Bulgarian limestone are perfectly proportioned and, inside, columns and ceilings swirl with an intricate cosmos of gods and deities hatched from shimmering white marble.
But it is the spirit behind its construction that verges on the miraculous - a place in modern Britain where the tide of faith is in full flood. The temple rose in just over three years, built largely by volunteers. It cost millions and they raised the entire sum themselves. They have just celebrated its first birthday.
A visit to the Mandir and to its new exhibition centre on Hinduism will prompt serious thought about wider and deeper questions of faith and identity. Britain now has nearly half a million Hindus.
The Swaminarayan movement is one of the largest groups, drawn primarily from immigrants from East Africa. Its first temple soon proved inadequate, so four years ago the movement's spiritual leader, Pramukh Swami Maharaj, called for the creation of the Mandir. It was to be the finest Hindu temple built in modern times. The architecture would observe ancient Vedic principles, each part expressing spiritual meaning.
The entire community put their shoulders to the task and tens of thousands attended the opening of the temple and, since then, many more have visited including more than 100 school parties. But tourists are still outnumbered by devotees.
A visit to the Mandir should be preceded by a tour of the adjoining exhibition which explains Hinduism, the history of the Swaminarayan movement and of the making of this temple. Getting to grips with Hinduism is hardest. Most Britons grow up in the shadow of God. Christians, Jews, Moslems and even non-believers find common ground in the idea of monotheism.
Hinduism also acknowledges one ultimate supreme creator of the universe and is defined by a rigorous need to live a disciplined moral life to achieve salvation. But step inside the temple and you are immediately aware that here is a very different concept of the cosmos. The Mandir offers a cavalcade of startlingly beautiful images of the gods, deities and gurus of an ancient religion that has been more than 3,000 years in the making.
All this is no mere decoration. When the temple's holymen prefaced its opening by parading their idols through London's West End the real purpose was to show the idols the streets of their new home town. Later, in the temple dedication, the Guru performed ancient rituals which, devotees believe, breathed life into these Murtis (idols). They believe they are now imbued with the living God.
The exhibition, however, throws only a degree of light on the mysteries at the heart of this faith. There is a lot to grapple with here. Schools planning to visit would do well to prepare with a few sessions on Hinduism first, though visiting groups will be allocated a guide and should not be shy about quizzing him on any concepts or ideas that baffle.
One of the things that worries many Hindu parents is assimilation and the inevitable challenge it presents to their culture, religion and community. One father said: "Many children say they don't ever want to go to India. They see TV reports about Indian poverty and social problems. My two boys didn't want to go, but I persuaded them and now they say they don't want to take holidays anywhere else."
Shri Swaminarayan Mandir 105115 Brentfield Road, Neasden, London NW10 8JP. Tel: 0181 965 2651 Fax: 0181 961 2444. Open daily from 9am until 6.30pm. Admission to Mandir and Haveli free. Admission to Hinduism exhibition: adults Pounds 2, children Pounds 1.50. Special rates for groups and school bookings at least three days in advance