Chennai district, formerly known as Madras district, is one of the 38 districts in the state of Tamil Nadu, India. It is the smallest and the most densely populated district in the state. The district is coterminous with the city of Chennai, which is administered by the Greater Chennai Corporation. It is surrounded by Tiruvallur district in the north and the west, Kanchipuram district in the south-west, Chenglpattu district in the south, and the Bay of Bengal in the east.