From the World Heritage inscription:
The Taj Mahal is located on the right bank of the Yamuna River in a vast Mughal garden that encompasses nearly 17 hectares, in the Agra District in Uttar Pradesh. It was built by Mughal Emperor Shah Jahan in memory of his wife Mumtaz Mahal with construction starting in 1632 AD and completed in 1648 AD, with the mosque, the guest house and the main gateway on the south, the outer courtyard and its cloisters were added subsequently and completed in 1653 AD. The existence of several historical and Quaranic inscriptions in Arabic script have facilitated setting the chronology of Taj Mahal. For its construction, masons, stonecutters, inlayers, carvers, painters, calligraphers, dome-builders and other artisans were requisitioned from the whole of the empire and also from the Central Asia and Iran. Ustad-Ahmad Lahori was the main architect of the Taj Mahal.
The Taj Mahal is considered to be the greatest architectural achievement in the whole range of Indo-Islamic architecture. Its recognised architectonic beauty has a rhythmic combination of solids and voids, concave and convex and light shadow; such as arches and domes further increases the aesthetic aspect. The colour combination of lush green scape reddish pathway and blue sky over it show cases the monument in ever-changing tints and moods. The relief work in marble and inlay with precious and semi-precious stones make it a monument apart.
There isn’t much to say about the Taj Mahal. It is one of the best-known structures on Earth. During the recent selection of the New Seven Wonders of the World, it was put on the list.
It is without question the single most identifiable thing associated with India. There are numerous Indian restaurants which use it as their name, and you can find a picture of it hanging in many others. If you are playing a video game like Civilization, the Taj Majal is almost always associated with India in some form.
Visiting the Taj Majal and seeing it in person, will convince you that all the attention and notoriety is well deserved.
There is nothing quite like it in scale or quality. If you visit other Mogul tombs before visiting the Taj (such has Humayun’s Tomb in Delhi or the nearby Little Taj in Agra) you will have a much greater appreciation just how magnificent it is. The earlier tombs can almost be considered beta versions of the Taj Mahal both in terms of size and quality.
If you visit the Taj Mahal, I highly recommend arriving as early as possible. The gates open at 7am. I arrived at 5:50am and was first in line. Being there first gives you and opportunity to take some photos without any people. Even 15 minutes after the gates open, the area will be filled with people. To do this you will have to stay overnight in Agra and not just take a day tour from Delhi.