The south Indian megalithic age exhibits a wonderful range of sepulchral and non sepulchral stone monuments erected possibly within 1100 BC–300 AD. However, building megalithic graves fell into disuse post-1000 AD for yet unknown reasons. The state of Tamil Nadu, southern India, hosts a large number of such megalithic sites and one monument, in particular, erected in the small panchayat town of Pallikonda, demands special attention. The site harbors a large, non-sepulchral stone arrangement comprising a large capstone balanced on three boulders. The entire structure lies at the foot of the large Pallikonda hill and overlooks the fertile basin of the Palar river. The capstone is oriented in the north-south axis, with a double projection that points towards north-west. Spatial analysis of the site reveals several unique features of the megalith. The structure is positioned strategically, so that a straight line drawn from the tip of the hill and passing through the north-west projection of the cap stone points towards the confluence of rivers Palar and Koundanyanadi, and on further extrapolation, to the summer solstice sunset. It is positioned at a point separating the arable from the non-arable lands. The capstone of the structure is dotted with cupules, some of which form distinct sightlines. Most of the sightlines match with the Iron age rising and setting azimuths of the stars Vega, Capella, Cassiopeia and Deneb. The study concludes that unique characteristics of the Pallikonda megalith mark it as a geographical, territorial and most possibly, as an astronomical marker.