Senji, immortalized by Desing's ballad, still popular in South India, is a significant place in the Tamil country. Successively occupied by the Hindus of Vijayanagar, the Nayakas, the Muslims of Bijapur, the Marathas, the Mughals and finally by the French in 1750, it was, at the end of the 16th century, one of the biggest cities of the peninsula. This study is an attempt to make an analysis of both the written documents and of the archaeological investigation: it is an essay at the junction of several disciplines (archaeology, history and human geography), trying to show the evolution of the defence systems of the stronghold, the development of the urban centre, as well as the different aspects of water and grain storage, which are at the root of its surprising growth.