Start your trip with a visit to Fort St. George, the first English fortress in India. Originally built in 1644 and now serving as the administrative headquarters for Tamil Nadu government, the fort's museum hosts a collection of artifacts from the colonial era including letters from Robert Clive and Siraj-ud-Daulah. You can also explore the nearby St. Mary's Church, the oldest surviving British Church in India.
Head to Marina Beach, the longest natural urban beach in the country. Its golden sand and clear blue waters provide a perfect escape from the hustle and bustle of the city. End the day by visiting San Thome Basilica, a stunning neo-Gothic church that was built in the 16th century over the tomb of St. Thomas, one of the twelve apostles of Jesus Christ.
Take a day trip to Mahabalipuram, a UNESCO World Heritage Site famous for its ancient rock-cut temples and exquisite stone carvings. Visit the Shore Temple, a beautiful temple overlooking the Bay of Bengal and Pancha Rathas, a collection of five monolithic temples carved out of single pieces of granite.
On your last day, visit the ancient Kapaleeshwarar Temple dedicated to Lord Shiva. This temple is famous for its intricate Dravidian architecture, colourful gopuram and the bustling market nearby. End your trip by reaching for the stars at the Birla Planetarium, which offers multiple shows on astronomy and the universe.
If you have extra time, you can head to Kanchipuram, the city of thousand temples or take a day trip to Pondicherry, the French Riviera of the East with its quaint French-style houses and serene beaches. Make sure to check the opening and closing times of the places you want to visit. You can also adjust the itinerary according to your preferences - add or subtract places based on your interests.