Explanation:

- Option 1: Bijapur

- The Gol Gumbad, also known as Gol Gumbaz, is indeed the mausoleum of Muhammad Adil Shah, Sultan of Bijapur.

- It is located in the city of Bijapur, Karnataka.

- This structure is famous for its massive dome and represents the architectural style of the Adil Shahi dynasty.

- Correct Answer: Bijapur

- Option 2: Allahabad

- Allahabad, now known as Prayagraj, is a city in Uttar Pradesh.

- It is primarily known for its religious significance and the confluence of rivers, not for Gol Gumbaz.

- Option 3: Delhi

- Delhi, the capital of India, has many historical monuments, but Gol Gumbaz is not one of them.

- Option 4: Agra

- Agra is known for the Taj Mahal and other Mughal architecture, but not for Gol Gumbaz.