Visit the Qutub Minar, the tallest free-standing brick minaret in the world, which stands 73 meters tall and is surrounded by beautiful greens and gardens. You can also explore the surrounding ruins of the ancient city of Mehrauli, including the Iron Pillar, Alai Darwaza, and the Tomb of Iltutmish.
Begin the day by visiting India Gate, one of the most famous landmarks in Delhi. This eternal flame war memorial is dedicated to the Indian soldiers who died in World War I. Afterward, visit the surrounding Children's Park, where kids can enjoy various rides and activities.
Visit the Red Fort, a historical Mughal fort made of red sandstone that was the residence of the Mughal Emperors. It is a UNESCO World Heritage site, having been designated as the symbol of India's sovereignty. Afterward, head to Lotus Temple, a beautiful temple with a lotus-shaped architecture that has won many architectural awards. The temple is surrounded by a garden and nine reflecting pools, creating an atmosphere of peace and tranquility.
If you have more time, consider adding a visit to Akshardham Temple, a magnificent Hindu temple, or Humayun's Tomb, another UNESCO world heritage site consisting of beautiful Mughal architecture. However, if you have less time, consider cutting down the itinerary to only visiting Qutub Minar and Red Fort. The India Gate and Children's Park could also be done in a shorter time frame depending on your family's interests.