Pallid portrait of a treasured tomb

ArchitectureThe Taj Mahal was a photo-opportunity even before cameras were invented. The image of the white marble mausoleum in Agra, northern India, has in the last few hundred years become to that country what the Pyramids have been for thousands of years to Egypt.

When it came to a good photo-opportunity, the late Diana, Princess of Wales had come to understand the power of a potent, symbolic backdrop. There she was in 1992, on the front page of countless magazines and newspapers, legs placed demurely sideways, eyes cast down, on a bench slap-bang in front of a 350-year old tribute to a royal wife. The mausoleum had been built as an expression of Moghul emperor Shah Jahan's love for his wife, Mumtaz Mahal. Diana's royal husband was infamously notable for his absence in those pictures. As Diana would so soon tell Martin Bashir on Panorama, "There were three of us in the marriage". As it happens, there were four "of us" in Shah Jahan's marriage, since he had three wives. But unlike the ill-fated Diana, Mumtaz Mahal proved to be the favourite in that crowded alliance.

This book's title comes from a surprisingly saccharine description of the Taj Mahal by India's Nobel-winning poet Rabindranath Tagore. Even he, a man so accomplished when it came to words, was apparently failed by words when it came to describing the Taj.

Mumtaz Mahal died in 1631 while giving birth to her 14th child, at the age of 38. She had had so many children, she was "a mine teeming with gems of royalty", according to the court chronicles of the time. In the Islamic tradition, women who died in childbirth were martyrs and their burial places were deemed places of pilgrimage. Shah Jahan chose a rural site for Mumtaz's mausoleum by the Jumna River, which was then distant from the busy city of Agra (today, the city surrounds it).

Even for an era when the rich were absurdly rich, the materials used in the decoration of the Taj were eye-popping in their extravagance. Of the 40 kinds of gems used as inlay in the Taj Mahal, jade was brought from Kashgar in China, lapis lazuli was mined in Afghanistan, turquoise came by yak from Tiber, rubies from Sri Lanka and coral from Arabia. However, contrary to popular belief, the mausoleum itself is not solid white marble, but brick with marble-faced slabs. The Prestons repeat the now-popular phrase about the Taj: that it was "built by giants and finished by jewellers". Lord Curzon, British viceroy in India at the beginning of the 20th century, was to report of the same jewels: "when picnic parties were held in the garden of the Taj, it was not an uncommon thing for the revellers to arm themselves with hammer and chisel with which they whiled away the afternoon by chipping out fragments of agate and carnelian from the cenotaphs of the emperor and his lamented queen".

This book, written by husband and wife team Diana and Michael Preston, who frequently collaborate on similar projects, is a very odd read. It mixes as many hard facts as are known about the particular Moghul period, Shah Jahan's life and that of his wife, with fanciful conjecture: their sex life for instance, is imagined in passages so dreadful any editor of romance novels would edit them out. The Prestons attempt to recreate the social, historical and political era in which the Shan and Mumtaz lived, but they do so with very limited success: perhaps all books of co-authorship run the risk of ending up with such a bland style, in order to mask the joins. Who, you can't help wondering crossly, especially in this crowded market of India-related books, is this dull and poorly-written book aimed at? Not even the pictures make up for the text, because impossible as it seems, the few that are present make the Taj look dull as an unimaginative municipal building. And they even left out that picture of Diana.

Rosita Boland is a writer and an Irish Times journalist

A Teardrop on the Cheek of Time: The Story of the Taj Mahal By Diana and Michael Preston Doubleday, 354pp. £16.99