Diu, also known as Diu Town, is a medieval fortified town in Diu district in the union territory of Dadra and Nagar Haveli and Daman and Diu, In…Diu, also known as Diu Town, is a medieval fortified town in Diu district in the union territory of Dadra and Nagar Haveli and Daman and Diu, India. Diu district is the tenth least populated district of India. The town of Diu lies at the eastern end of Diu Island and is known for its fortress and old Portuguese cathedral. It is a fishing town.