Mariamman Teppakkulam Tank Madurai

This vast tank, 3km east of the old city, covers an area as big as the Meenakshi Amman Temple and is the site of the incredible annual Teppam (Float) Festival. It's empty most of the year, when it primarily serves as a cricket ground for local kids. It was built by Tirumalai Nayak in 1646 and is connected to the Vaigai River by underground channels.