Explore the UNESCO World Heritage Site of Mahabalipuram which has a rich history dating back to the 7th century. Admire the intricately carved cave temples, monolithic rathas, and the spectacular Shore Temple. Visit the Arjuna's Penance which is an enormous bas-relief carving, depicting a scene from one of the Indian mythologies. You can also check out the Five Rathas which are five monolithic temples shaped in different styles. End the day with a walk along the beach admiring the beautiful sunset.
Explore the capital city of Tamil Nadu, Chennai. Start with a visit to the famous Marina Beach which is one of the longest urban beaches in the world. Visit Fort St. George which was built by the British East India Company in 1644 AD. Stroll around the Government Museum that has a gallery of traditional South Indian bronzes and amazing artefacts from the Indus Valley Civilisation. To end your day visit the Kapaleeshwarar Temple, which is considered one of the finest examples of Dravidian architecture.
If you have more time, consider visiting Kanchipuram, which is known as the City of Thousand Temples. Home to several historic temples and renowned for its silk sarees. Or you can spend a day exploring the city's food scenes, especially their famous street food.
If you have less time or looking for something specific to do, then you can consider visiting Dakshina Chitra, which is a heritage museum that showcases the various cultures of South India. You will find recreated traditional houses and informative documentaries on South Indian art, craft, and architecture.