The Path to the Taj
Kamal Lodaya, The Institute of Mathematical Sciences, Chennai

In the beginning
In 1192 CE, Muhammad Ghuri, from the Ghur region of Afghanistan, defeated Prithviraj Chauhan, king of Ajmer, at the battle of Tarain (near Delhi). Two years later, King Jayachandra Gahadvala of Kanauj was also defeated. 
You may wonder why the two kings did not fight together against a common enemy, but there was no idea of a unified India at that time. The armies on the Indian side were only put together when a king requested soldiers from his nobles. They relied on elephants.
The Afghan army had much better horses from Arabia and Central Asia. They had archers who could use a bow even on a horse. Their soldiers were slaves who were trained to become professionals. The Turki slave and army general, Qutb ud-din Aibak, remained in Delhi and set up the first Islamic empire in India.

Qutb ud-din Aibak
To celebrate his victories, and in imitation of his masters who had done the same thing in Jam in Afghanistan, Qutb ud-din built a brick minar, then the tallest in the world at 83 metres. It was next to the Qubbat al-Islam (Sanctuary of Islam) mosque, which was also newly built. 
You may think the minar was for the maulvi to call the azan, which tells the faithful Muslim that it is time to pray. But at that height at the top, no azan could be heard. The walls of the mosque had Arabic quotations from the Quran, Islam's holy book. The minar only had Persian inscriptions proclaiming the Ghuris as kings of Arabia and Persia. So the purpose of the minar was political as well as religious. Today it is called the Quwwat al-Islam (Strength of Islam) mosque.
Islam also entered in the form of Sufi saints like Moin ud-din Chishti (who died in 1236) and Nizam ud-din Auliya (who died in 1325). The latter was said to be more popular and in rivalry with the then sultan, Ala ud-din Khalji. Perhaps because of this, the sultan added a red and white sandstone entrance, the Alai Darwaza, to the Qubbat mosque. Its design and colours are derived from the Turkish Seljuks of central Asia, many of whom fled to India from the Mongols who were raiding that region.
With Islamic rulers, north India was then seen as a home for Islam. The Tughlaqs who ruled Delhi next (in the 14th century) constructed mosques, madrasas (schools) and other civil works. They also contributed to the construction of Hindu temples. It was much later that the Hindu nobles under the Mughals, such as Raja Man Singh, contributed to the construction of Islamic buildings. 

Sikandar Shah
The Adina mosque at Pandua near Malda, Bengal, was built in 1375 by its ruler Sikandar Shah who defeated the Tughlaqs. Modelled on the great mosque of Damascus, Syria, at the time of its construction the Adina was the largest mosque in the world. It is now largely in ruins, due to earthquake damage.
In its mihrabs (prayer niches), lamps were carved, referring to a Quranic verse which compares Allah's presence to "light in a niche". The idea of light (noor) was taken very seriously by the Mughals who came later. For example, Jahangir named his wife Mehrunnissa as Noor Mahal (Light of the palace) and later Noor Jahan (light of the world). 

Babar, the first of the Moghuls
In 1526 Jamal ud-din Babar, a descendant of the Mongols, defeated Ibrahim Lodi at the first battle of Panipat, north of Delhi. In addition to fast-moving cavalry (horsemen) he used light cannon and guns shielded by a barricade of carts. Although his army and nobles disliked the heat and dust of north India, Babar stayed on. 
Babar was very fond of the plants, flowers and fruits of his native Farghana and Samarkand (now in Uzbekistan). He introduced the idea of a charbagh, a garden divided into four parts by water channels. He constructed several, especially in his capital Agra along the Yamuna river, but most of them are no longer present. All the later Mughal kings also took the construction of gardens seriously. Jahangir constructed several gardens in Kashmir and in Lahore.

Humayun, son of Babar
Babar's son Humayun was chased out of India in 1540 by Sher Shah Suri, an Afghan/Pashtun ruler from Bihar. Sher Shah is known for his construction of the Grand Trunk Road from Bengal to Afghanistan, with sarais (inns) for travellers to stay. He also built mosques and forts. The Qila i-Kuhna mosque in Delhi from 1528 improves upon the Alai Darwaza. Its architect was Ahmad Niyazi and it is located in the Qila i-Kuhna or Old Fort area.

Sher Shah Suri
Sher Shah came from a humble background. Perhaps because of this, he built a grand tomb for his grandfather Ibrahim Khan at Narnaul, for his father Hasan Shah, and an even bigger octagonal one for himself in Sasaram, inside an artificial lake. The eight sides represent an Islamic idea of eight stages to reach paradise. Until the time of Sher Shah, public construction of rauzas (tombs) was only for saints, such as the one for Shaikh Ahmad Khattu at Sarkhej near Ahmadabad.

Akbar and Humayun's Tomb
Today we see Humayun's son Jalal ud-din Akbar as the greatest Mughal emperor. A lot of the administrative machinery he set up was started by Sher Shah. Perhaps Akbar was determined to be better than Sher Shah in all areas when he came to power in 1556.
From 1562 to 1572 his father Humayun's tomb (see cover photo) was constructed in Delhi, just across from the dargah of Nizam ud-din Auliya, the Sufi saint. Thus Akbar connects his family to the Chishti saints like Moin ud-din and Nizam ud-din. A landscape architect from central Asia, Muhammad i-Mirak Mirza, was invited for the design and construction. The tomb is placed in the middle of a charbagh, and is meant to evoke an idea of paradise on earth. This is one of the world's great monuments.

Akbar and Fatehpur Sikri
From 1569 to 1584, Akbar constructed his new capital Fatehpur Sikri outside Agra, whose design and red sandstone construction is breathtaking. The Buland Darwaza was meant to be bigger than any other in the world. It has Islamic verses calligraphed on it, written in gigantic letters to be visible from below.
Inside Fatehpur Sikri, Akbar constructed a white marble tomb for Shaikh Salim ud-din Chishti, who had predicted the birth of his son. Akbar used architects and builders from all over India. The design of the city was done by Bengali architect Tuhir Das. The jali (screen) work, for example in Shaikh Salim's tomb, is said to be based on work of Gujarati builders. Although Akbar was illiterate (modern historians believe he was dyslexic) it is known that he took a great deal of interest in the design and architecture of Fatehpur Sikri.

Noor Jahan
Noor Jahan, Jahangir's twentieth and favourite wife, constructed many monuments. The tomb in Agra for her parents Asmat Begum and Mirza Ghiyas Beg, whom Jahangir named Itimad-al-Daula (pillar of empire), was completed in 1628. It is called a "jewel box" for its intricately carved structure. It is built entirely of white marble inlaid with semi-precious stones and laid on a red sandstone plinth. It has four turrets which are between minars and the chhatris of Rajasthan. Jahangir had earlier used chhatris for Akbar's tomb at Sikandra near Agra.

The path leads here
Jahangir's son Khurram, or Shah Jahan, married Noor Jahan's niece Arjumand Banu Begum after a five-year engagement. She died after bearing him 14 children while she was accompanying him on a campaign in Burhanpur, Madhya Pradesh. The heartbroken Shah Jahan built her a Rauza i-Munawwar (the name is the same as of prophet Muhammad's tomb in Medina, Arabia). It has white marble, also some black marble and inlays with semi-precious stones. There are chhatris and four elegant minars. In front is a charbagh which had a profusion of fruits and vegetables; the British who ruled India replaced this with grass lawns.
The beautiful room where the bodies of Arjumand Banu, and later Shah Jahan, were laid, is modelled after the one constructed by Noor Jahan for her parents. Twenty thousand workers are said to have worked on the monument for 22 years. There is a conscious use of the sunlight falling on the structure at different times of the day.
The main architect is believed to be Ahmad Lahori, the calligraphy is said to be by Abdul Karim Shirazi and the cosntruction by Makramat Khan. Today it is known by the name Shah Jahan gave his wife, Mumtaz Mahal (Jewel of the palace)---the Taj Mahal, regarded as one of the finest examples of Moghul architecture.