President George Bush this week visits India -- the home of not just a masterpiece, but of one of the great wonders of the world.
The Taj Mahal is, like the Mona Lisa, one of those masterpieces with which you will be outstandingly familiar long before you ever get to see it.
There is not a camera-wielding tourist in the world who will not have seen many pictures of the Taj's onion dome and her four towering minarets.
All too often, this familiarity can lead to disappointment when you finally see the original. I well remember the let-down of seeing the Mona Lisa for the first time, smaller than I'd imagined and lost amid a swirling gaggle of tourists.
But the Taj Mahal does not disappoint. It does not disappoint the first time you see it, nor the third time, nor even the 30th time.
This may be because the Taj's appearance is constantly changing. It might sound strange to say this of an inanimate building, but every time you see the Taj, it looks different. The color of its white marble changes throughout the day, from the waxy yellow at dawn through to the pastel blue-gray of a full moon.
From every angle, the Taj reveals new facets. It has the sort of majestic beauty that catches you quite unawares. You can be sitting in the lush grounds, admiring the cypresses or the palm trees, and then you look up, catch a glimpse of the Taj, and yet again its perfect curves take your breath away.
What is even more incredible is when you realize that Shah Jahan's spectacular project is only half-finished -- but more of that later.
The Taj is, according to almost every guidebook, the world's "greatest monument to love." The Mughal Emperor Shah Jahan had been married to Mumtaz Mahal for 18 years when she died giving birth to their 14th child.
After her death in 1631, Shah Jahan's hair is said to have turned white within the week. The entire country was ordered into mourning, and almost immediately Shah Jahan had conceived of building the most fabulous tomb the world had ever seen.
Monarch of all he surveyed, Shah Jahan was more than capable of turning such extravagant dreams into a reality. He was the fifth in an unbroken line of Mughal emperors who had ruled India for over a century. And although his name is now inextricably linked to love, Shah Jahan was as ruthless as any of his ancestors, dispatching four of his brothers before seizing the throne in 1628.
For 350 years, Agra was the main capital of the Mughal Empire, and it was here by the banks of the Yamuna River that Shah Jahan ordered Mumtaz's mausoleum to be built. Many of the facts about the building of the Taj have been lost, and much of what remains is a wealth of far-fetched theories and legends. We cannot even be certain about the name of the architect. Some believe the Taj was designed by the Turk Ustad Isa, while others claim it was Ahmad, a Persian engineer who'd been involved with several of the emperor's earlier works.
But although we know nothing of the architect, we know much more of the artisans who worked on the Taj. Ismail Afandi, from Turkey, designed the dome, which is a masterpiece in itself, bulging out slightly before it tapers back in, so that all its load is transferred directly downward. Qazim Khan, from Lahore, in what is now Pakistan, made the solid gold finial that would top the dome. And the calligrapher Amanat Khan, from Shiraz -- in modern-day Iran -- was in charge of all the Arabic lettering that was cut into the white marble. There is a charming etching of his signature at the base of the interior dome: "Written by the insignificant being, Amanat Khan Shirazi."
Some 20,000 workers took 20 years to build the Taj. At first, it was just a job of brute force, moving thousands of white marble blocks a distance of 120 miles. But after the main building had been completed, the most lavish detail was added. Jade and crystal were shipped in from China, lapis lazuli from Afghanistan. And coral and mother-of-pearl were garnered from the Indian Ocean. The tomb itself had gold lamps and a door of solid jasper, and was guarded by gates of silver. Sadly, the Taj was long ago plundered of its loot, and all that remains in the crypt are the ornate marble tombs of Shah Jahan and his Mumtaz.
Shah Jahan was said to have been so delighted with the end result that he had the architect beheaded, the better to ensure that no other building would ever rival the Taj. Even to this day, the emperor's wish would appear to have come true.
But we can only imagine what the Taj might look like if Shah Jahan's dream had been completed to the full. For later on in his life, he planned to build a black Taj for himself on the other side of the Yamuna. It was to have been every bit as magnificent as the white Taj, and the two were to have been connected with a bridge of solid silver.
In true Mughal style, however, Shah Jahan was deposed by his son Aurangzeb, who had far better things to do than complete his father's tomb. Shah Jahan spent his last eight years imprisoned in the nearby Agra Fort, from where he would daily gaze at his life's work.
Sometimes though, if the light is right, you can squint at the Taj and see the spectre of its black twin on the other side of the Yamuna -- and it is then that you truly marvel not just at the Taj, but at the wonder of what might have been.