Ala'i Dharwaza (Alauddin's gate), Delhi - first tall dome built in India - a UNESCO world heritage site

Ala'i Darwaza, Delhi,
Ala'i Darwaza, also known as  the Gate of Alauddin) has the credit being  the first Indian monument to be built using Islamic style of architecture, construction techniques and ornamentation . A World Heritage Site recognized in 1993, it forms the southern gateway of the Quwwat-ul-Islam Mosque in Qutb complex, Mehrauli, Delhi, India. This  square domed gatehouse has  arched entrances with  a single chamber. It was built by Sultan Alauddin Khalji in 1311  and the impressive feature is it is made of red sand stones.  
Alauddin Khalji, DelhiSultenate.
  Alauddin Khalji and malik Kaufer, Khalji, a bisexual.
 Alauddin Khalji (of the Khalji dynasty) (r. 1296–1316) was the second and the most powerful ruler of the Khalji dynasty that ruled the Delhi Sultanate in the Indian subcontinent. He was a good warrior and war strategist.
Alauddin Khalji, silver coins, Delhi.
 Born as Ali Gurshasp, Alauddin was a nephew and a son-in-law of his predecessor Jalaluddin. When Jalaluddin became the Sultan of Delhi after deposing the Mamluks, Alauddin was given the position of Amir-i-Tuzuk (equivalent to master of ceremonies). Alauddin obtained the governorship of Kara in 1291 after suppressing a revolt against Jalaluddin, and the governorship of Awadh in 1296 after a profitable raid on Bhilsa. His greed led him to kill  Jalaluddin, and subjugate his sons in Multan. Between 1297 and 1306, he successfully tackled the Mongol invasions from the north.

In the winter of 1302–1303, Alauddin's army marched to the Kakatiya capital Warangal to ransack it. While  Alauddin' himself led another army to conquer Chittor, the capital of the Guhila kingdom ruled by Ratnasimha. The siege was a long one - roughly 8 months  and at last Alauddin captured Chittor.  According to his courtier Amir Khusrow, he ordered a massacre of 30,000 local Hindus after this conquest.  Some later legends mention  that Alauddin invaded Chittor to  with a view to capturin Ratnasimha's beautiful queen Padmini. Many historians  reject this story as it does not have any valid records. It is more of a conjecture than of a true story.
1870s Ala'i Darwaza, Delhi,
  His  army's  successful raid  under Malik Kaufer on Devagiri in 1308, that was ruled by king Ramachandra, further encouraged Alauddin  to plan a large scale invasion of Devagiri.  In late 1309, he sent Malik Kafur to loot the Kakatiya capital Warangal. and in January 1310, the army plundered the towns and villages on his way to Warangal. In the wake of a long  siege of Warangal, the Kakatiya king Prataparudra agreed to become a tributary of Alauddin, and surrendered a large amount of wealth (apparently including the Koh-i-Noor diamond) to the invaders.

Malik Kafur, upon knowing the affluence the Hoysala and Pandya kingdoms in southern India, he  took yet another expedition to go on a plundering spree. With consent from the Sultan,  Kafur started his march from Delhi in November 1310.  At this time, in the Pandya kingdom a war of succession  was on between the two brothers Veera Pandya and Sundara Pandya. The  Hoysala king Ballala  wanted to take advantage of this revelry in the Pandya royal family.  When Kafur's army marched into his place capital Dwarasamudra after a brief war king Ballala, to save his head, negotiated a truce, agreeing to surrender his wealth and become a tributary of Alauddin.

From Dwarasamudra, Malik Kafur's raid to the Pandya kingdom
was quite profitable.  Both Vira Pandya  and Sundara Pandya fled their capital Madurai and the Pandy rulers never became a tributary. The Delhi army's loot  was a large one - lots of treasures, elephants and horses. The Delhi chronicler Ziauddin Barani described this seizure of wealth from Dwarasamudra and the Pandya kingdom as the greatest one since the Muslim capture of Delhi.

Despite being a religious fanatic, Khaliji, was, no doubt, a good administrator and for better governance, he introduced revenue reforms, market reforms (control on prices) and social reforms such as a  ban on alcohol drinking, smoking of cannabis, gambling, prostitution, etc. Adultery was a taboo during his rule.  Alauddin  introduced serious punishments: in the case of  male adulterer he will be  castrated; as for  female adulterer, she will be stoned to death. He had a check on the nobility to prevent rebellions against him.  His revenue reforms were popular. Alauddin Khalji's taxation system has survived  into the nineteenth or even the twentieth century. From now on, the land tax (kharaj or mal) became the principal form in which the peasant's surplus was expropriated by the ruling class.
    — The Cambridge Economic History of India: c.1200-c.1750,
Alauddin, being a Sunni Muslim and fanatic, is reported to have destroyed several Hindu temples during their military campaigns. These temples included the ones at Bhilsa (1292), Devagiri (1295), Vijapur (1298–1310), Somnath (1299), Jhain (1301), Chidambaram (1311) and Madurai (1311). Yet another temple affected in Tamil Nadu was Srirangam in 1311 when Malik Kaufer raided this temple town. The worst one took place on 8 March 1323 under Ulagh Khan during the Panguni festival.  The ''Kozhil olugu'', book on history and temple administration of Srirangam narrates this invasion as ''Panniraayiravar mudi thiruthiya mettu kalagam'' meaning story of 12000 people (Vaishnavites) beheaded by the Muslim invader. ( ..............................

Alauddin commissioned the Alai Darwaza, that was completed in 1311 to serve as  the southern gateway leading to the Quwwat-ul-Islam mosque built by Qutb al-Din Aibak.  He also began  the construction of the Alai Minar, which was intended to be twice  the size of the Qutb Minar, but the project was abandoned,  presumably due to his death.
It was a part of his plan to extend the Quwwat-ul-Islam Mosque on four sides. Though he planned to build four gates, only the Alai Darwaza could be completed. The gate is made up of a single hall whose interior part measures 34.5 feet (10.5 m) and exterior part measures 56.5 feet (17.2 m). It is 60 feet (18 m) tall and the walls are 11 feet (3.4 m) thick.
Stone window, Ala'i Darwaza, Delh,
Left:Qutbminar,the unfinished Alai Minar, Delhi
 The structure shows bold contrasting colors of masonry, with red sandstone and white marble and this introduction later became  a common feature of Indo-Islamic architecture, substituting for the poly chrome tiles used in Persia and Central Asia. yet another feature that is commonly found in the Hindu temples is the stone screens - jalli. This dome standing up to a height of 47 feet, is believed to the first one in India. The red sand stones and the marble stones inlaid on the exterior walls make this monument impressive. The other inspiring features are the extensive Arabic calligraphy on the walls of the Darwaza,  horseshoe shaped arches  ( for the first time such arches were used in India), pre-Turkish carvings and patterns on the facades, lattice marble windows and   surface decorations - inter weaved floral tendrils
repeated with a symmetry on three doorways

Alauddin died on the night of 4 January 1316. Barani claims that according to "some people", Kafur killed him and brought  his body  from the Siri Place and had it buried in Alauddin's mausoleum that had already been built by the ruler.)