Delhi: Adventures In A Megacity, By Sam Miller

As Indian megacities go, Delhi is often thought of as lacking the vitality of Bombay and Calcutta, an uninspiring administrative capital when compared to those seething entrepôts. Not so, as Sam Miller shows us in his engaging and innovative account - innovative, because for an ostensibly staid BBC journalist he uses a distinctly alternative approach, drawing upon psychogeographic techniques championed by Iain Sinclair and other writers.

Miller's strategy is simple. He draws a spiral upon a map of Delhi and walks the route it dictates. Very often the resulting journal appears more of a success than similar exercises in London and other developed cities, because Delhi lends itself so well to the process.

Normally, its residents and visitors stay within well-defined comfort zones and do not encounter the city's full range of staggering contrasts. Some of them relate to deeply rooted cultural diversity, others to massively unequal divisions of wealth: most of the city's new riches have yet to permeate its urban fabric and the conditions endured by many inhabitants are barely credible.

Miller has a hugely eclectic variety of experiences at pavement level. He visits ancient palaces and gleaming new metro stations. He passes express highways, including an inner ring road which slices across the city - sometimes literally - as it ruthlessly dissects dwellings in its path. In Old Delhi, he walks into an open-air slaughterhouse which is the stuff of nightmares and, later, manages to stay just a few paces ahead of man-eating pigs.

Ordure becomes a running (or walking) theme. In Paharganj he watches backpackers fret over bowel problems, ready prey for touts including the cunning shoe-shiners of Connaught Place, who direct secret squirts of excrement onto foreigners' footwear before offering their clean-up services.

Alongside the prosperous neighbourhood of Jangpura, Miller wanders into a slum for Bangladeshi immigrants which is substantially sited in an open sewer. The city's main watercourse, the Yamuna River, is itself a huge reeking drain that at Nigambodh Ghat becomes a site for open-air cremations.

There is some fresh air. One of Delhi's unexpected aspects is the deserted stretch of open countryside running through the city: the Ridge, or northernmost extension of the Aravalli mountain range. Prominent residents are Prince Cyrus and Princess Sakina of Oudh, living in aloof dilapidation.

The appeal of Miller's journey is in its random minutiae. The dots of colour in his elegant spiral accumulate into an intimately rounded portrait, but this snapshot is part of a wider picture of ferocious aggrandisement. Greater Delhi is set to have 64 million inhabitants by 2021.

In the 17th century, under Mughal rule, this was said to be the world's most populous city. As India assumes superpower status, it might well soon become so again.