The Qutub Minar is the largest freestanding brick minaret in the world. It is 239 feet high and 14.3 meters in diameter at the base. It's a prime example of Indo-Islamic architecture.
Because I'm not sure if you'll click a link to learn more, here's some info from Wiki:
"Inspired by the Minaret of Jam in Afghanistan and wishing to surpass it, Qutb-ud-din Aibak, the first Muslim ruler of Delhi, commenced construction of the Qutub Minar in 1193, but could only complete its base. His successor, Iltutmish, added three more stories and, in 1368, Firuz Shah Tughluq constructed the fifth and the last story. The development of architectural styles from Aibak to Tuglak are quite evident in the minaret. Like earlier towers erected by the Ghaznavids and Ghurids in Afghanistan, the Qutub Minar comprises several superposed flanged and cylindrical shafts, separated by balconies carried on Muqarnas corbels. The minaret is made of fluted red sandstone covered with intricate carvings and verses from the Qur'an. The Qutub Minar is itself built on the ruins of Lal Kot, the Red Citadel in the city of Dhillika, the capital of the Tomars and the Chauhans, the last Hindu rulers of Delhi.
The purpose for building this monument has been variously speculated upon. It could take the usual role of a minaret, calling people for prayer in the Quwwat-ul-Islam mosque, the earliest extant mosque built by the Delhi Sultans. Other possibilities are a tower of victory, a monument signifying the might of Islam, or a watch tower for defense. Controversy also surrounds the origins for the name of the tower. Many historians believe that the Qutub Minar was named after the first Turkish sultan, Qutb-ud-din Aibak but others contend that it was named in honour of Qutbuddin Bakhtiar Kaki, a saint from Baghdad who came to live in India and was greatly venerated by Iltutmish."