The correct answer is Taj Mahal.

• Agra is know for Taj Mahal (Tomb of Mumtaz Mahal, built by the Mughal emperor Shah Jahan for the memory of his favourite wife).
• The Taj Mahal is in the list of UNESCO World Heritage Site since 1983.
• Ustad Ahmad Lahauri was the chief architect of Taj mahal.
• Construction of Taj Mahal was started in AD 1632 and was completed in late 1648 AD

• Agra Fort is a historical fort in the city of Agra in India. It was the main residence of the emperors of the Mughal Dynasty until1638.
• Moti Masjid inside Agra Fort was built by Mughal emperor Shah jahan.
• The tomb of Akbar is at sikandra, approximately 8 km from main city of Agra.
• Fatehpur Sikri is a town in the Agra District, known for Buland Darwaza, and Tomb of Salim Chishti, the city itself was founded as the capital of Mughal Empire in 1571 by Emperor Akbar to 1585.

• Red Fort was built by Mughal emperors Shah Jahan. 
  • Construction of Red Fort was started in AD 1639 and was completed in late 1648 AD. 
  • Ustad Ahmad Lahauri was the chief architect of Red Fort .
  • Moti Masjid inside Red Fort, Delhi was built by Aurangzeb.
  • Red Fort is in the list of UNESCO World Heritage Site since 2007.
• Qutub Minar is the  world's tallest minaret built of bricks.
  • The height of Qutb Minar is about 73 meters.
  • The construction of Qutub Minar was started by Qutb-ud-din Aibak (Founder of the Slave Dynasty) and completed by Shamsuddin Iltutmish(Second ruler of Slave Dynasty).
  • The topmost storey was built by Firoz Shah Tughlaq of Tughlaq Dynasty.
  • Qutub Minar is in the list of UNESCO World Heritage Site.