If Bangalore is India's IT capital and the beaches of Goa are its hedonistic playground, then Agra's Taj Mahal must surely be the heart of the country. Built in memory of the Moghul emperor Shah Jahan's beloved wife Mumtaz, there can be few monuments to a lost loved one as impressive as this gleaming white marble temple. It took around 20,000 workers more than 20 years in the 17th century to create India's most recognisable symbol of Moghul architecture.
Situated on the south-eastern tip of the popular tourist trail of the "Golden Triangle" (the other two points being Delhi to the north and the "pink city" of Jaipur to the south-west), Agra is located within the Indian state of Uttar Pradesh, and was the imperial capital for more than a century during the Moghul era.
But it is to the Taj Mahal (often referred to simply as "The Taj") that visitors flock in their millions today. An incredible building constructed entirely of white marble, the Taj stands at the edge of the Yamuna river, looking back over the city of Agra and its fort, which itself dates back to the 16th century. The temple is best visited at dawn, not only because the site is less crowded but also to witness the Taj gradually taking on its shining white appearance as the sun rises into the hazy sky. Legend has it that Shah Jahan planned a second identical "Black Taj" across the river to house his body upon his death, although the evidence for this is sketchy.
Apart from the sheer workmanship required to build an entire temple from marble, the other remarkable feature of the Taj is its almost perfect symmetry. The buildings, gardens, walkways, pillars and domes all combine to create a scene that could be folded in two both vertically and horizontally, as the symmetry is repeated by the reflection of the Taj in the central watercourse leading up to the temple steps and its famous onion dome. Thousands of semi-precious gems decorate the temple, and even the calligraphy has been painstakingly created from pieces of black marble inset into the walls.
The Taj is often described as one of the seven modern wonders of the world, and later this year it may finally be able to lay official claim to this accolade. Back in 2000, a search was started to find the seven sites most deserving of the title, and from hundreds of entries the list has been whittled down to just 21 finalists, which now face the public vote in a sort of X-Factor contest for the monuments of the world. Unsurprisingly, the Taj Mahal has made it through to the final vote, alongside such wonders as the Eiffel Tower, Machu Picchu, the Great Wall of China, Stonehenge and the Statue of Liberty. More than 20 million votes have been received so far, with the final line-up due to be announced on July 7.
Meanwhile, the Taj is involved in another race, one that threatens its existence far more than an arbitrary inclusion on the world's "most loved" list. The temple has been diagnosed with a type of "marble cancer", effectively a yellow fungal covering caused by the concentration of sulphur dioxide in the atmosphere – the result of years of pollution from belching factories and the huge volume of traffic serving Agra's ten million plus inhabitants, not to mention the millions of tourists who visit the Taj each year.
The government has gone some way to addressing the issue by banning petrol and diesel vehicles from coming within one and a half kilometres of the temple (an electric bus is now in operation), as well as creating an exclusion zone of more than 10,000 square kilometres around the site to prevent the building of any new factories. It has also controversially increased the entrance fee for foreigners from a few rupees to Rs 750 (£8.70) in order to deter such large numbers of visitors and also to raise funds to help with the restoration of the temple. But it remains to be seen whether these measures will curb the damage being caused to the Taj – when I visited the temple a constant smoggy haze hung in the air around Agra, and on a bad day it is impossible to see across the river to the city's fort, a mere two kilometres from the Taj.
This modern-day tragedy is not the only one to have threatened the chocolate-box love story of the Taj. Before the building was finished, Shah Jahan found himself imprisoned by his own power-hungry son in Agra's fort, and was forced to watch the construction of the monument from across the river until his death in 1666. He did eventually return to the temple however, when his body was laid to rest alongside that of his beloved Mumtaz – his cenotaph is one of the few constructions within the temple to break with the symmetry of the building.
For all the tourists, the smog, and the seemingly interminable journey to get to Agra (official estimates of three hours from Delhi by road belie the near six-hour journey I encountered along the region's clogged highways), there is no doubt that a visit to northern India is not complete without catching a glimpse of the Taj Mahal. It is hard not to be moved by the romantic story surrounding India's most famous building – as the poet Tagore once wrote, the Taj Mahal is "like a teardrop on the cheek of time". It can only be hoped that the temple survives the ravages of modern Indian life to delight another generation of lovers.
The Taj Mahal is open Sat-Thurs 0600-1900. Admission is currently Rs 750 (£8.70). For more information visit incredibleindia.org, and to vote for your favourite modern wonder of the world visit new7wonders.com.