Visit the first garden-tomb on the Indian subcontinent, a UNESCO World Heritage site. The tomb's design is based on the Arabesque which came to India during the Mughal period. Spend a few hours admiring the intricate details and peaceful surroundings.
Head to the Red Fort, a historic fort constructed during the Mughal Empire. It was the main residence of the emperors until 1857. The site houses a number of museums, galleries, and monuments.
Visit the Qutub Minar, a soaring 73-meter tower built-in 1193 by Qutab-ud-din Aibak. Explore the adjacent mosque which is the first mosque to be built-in India.
Head to the Lotus temple, a Bahá'í House of Worship which is shaped in the form of a lotus flower. It's a place of worship open to all faiths where visitors can peacefully meditate and experience the serenity of the place.
If you have extra time, consider visiting the India Gate, Raj Ghat, Akshardham temple, or Jama Masjid. For a more in-depth understanding of the Indian culture, attend a local festival or bazaar. If you have less time, you can remove one of the sites from the itinerary. Make sure to check the opening hours of the sites before you visit.