In which one of the following buildings the first extant true arch is found ?

The Tomb of Sultan Balban, located in the Mehrauli Archaeological Park and dating to approximately 1287 AD, is widely recognized by historians as the first building in India to feature a true arch constructed with the scientific method of voussoirs. While earlier structures like the Quwwat-ul-Islam Mosque and the Adhai Din Ka Jhonpra utilized the corbelled or 'false' arch technique due to the reliance on local artisans unfamiliar with Islamic structural engineering, Balban's tomb represents a critical transition in Indo-Islamic architecture. Although the Alai Darwaza (1311 AD) is often cited as the first building to employ a 'true dome' and fully realized Islamic principles with precision [2], the extant remains of Balban's tomb provide the earliest surviving evidence of the true arch's structural application in the Indian subcontinent.

Sources

1. [1] https://files.core.ac.uk/download/pdf/144518671.pdf
2. [2] History , class XI (Tamilnadu state board 2024 ed.) > Chapter 10: Advent of Arabs and Turks > Architecture > p. 152