Madurai is one of the major cities in the Indian state of Tamil Nadu. It is the administrative headquarters of Madurai District, the third largest city in Tamil Nadu and 25th most populated city in India. Located on the banks of River Vaigai, Madurai has been a major settlement for two millennia. Madurai is closely associated with the Tamil language, and the third Tamil Sangam, a major congregation of Tamil scholars said to have been held in the city. The recorded history of the city goes back to the 3rd century BCE, being mentioned by Megasthenes, the Greek ambassador to the Maurya empire, and Kautilya, a minister of the Mauryan emperor Chandragupta Maurya. Signs of human settlements and Roman trade links dating back to 300BC are evident from excavations by Archeological Survey of India in Manalur. The city is believed to be of significant antiquity and has been ruled, at different times, by the Pandyas, Cholas, Madurai Sultanate, Vijayanagar Empire, Madurai Nayaks, Carnatic kingdom, and the British East India Company British Raj. Rameswaram, (also spelt as Ramesvaram, Rameshwaram) is a town and a second grade municipality in the Ramanathapuram district in the South Indian state of Tamil Nadu. It is on Pamban Island separated from mainland India by the Pamban channel and is about 40 kilometres from Mannar Island, Sri Lanka. It is in the Gulf of Mannar, at the tip of the Indian peninsula. Pamban Island, also known as Rameswaram Island, is connected to mainland India by the Pamban Bridge. Rameswaram is the terminus of the railway line from Chennai and Madurai. Together with Varanasi, it is considered to be one of the holiest places in India to Hindus, and part of the Char Dham pilgrimage.