The Red Fort, a UNESCO World Heritage Site, is a must-visit attraction in Delhi. Built in the 17th century, this magnificent fortress-cum-palace is a stunning example of Mughal architecture. In the morning, explore the fort's many buildings and gardens. After lunch, visit the nearby Chandni Chowk market, where you can find everything from jewellery to spices. In the evening, take a stroll around the fort's perimeter and enjoy the light and sound show.
Humayun's Tomb, another UNESCO World Heritage Site, is a beautiful example of Mughal architecture. Built in the 16th century, it is the final resting place of Mughal Emperor Humayun. In the morning, explore the tomb and its surrounding gardens. After lunch, visit the nearby National Museum, where you can see a fascinating collection of Indian art and artefacts. In the evening, head to the nearby India Gate, a war memorial that's especially beautiful at night.
Other family-friendly attractions to consider include the Lotus Temple, the Akshardham Temple and the National Zoological Park. If you have more time, consider taking a day trip to Agra to see the Taj Mahal.