The Site of Raja Bersiong's Fort (GPS: 5.56421, 100.50981) is at Kota Aur, in southern Kedah. Now there are four different sites in the area that are possible, but the most likely one, I am told, is at Kampung Tok Soh in Pinang Tunggal.
Raja Bersiong is the nickname for Ong Maha Perita Deria, also called Seri Maha Inderawangsa. The fifth ruler of the pre-Islamic kingdom of Kedah, he is said to be a bloodthirty despot who turned Gunung Keriang and Tunjang into his hunting ground. Raja Bersiong got its nickname because he wore boar tusks around his neck as a sign of manhood. However, latter stories attributed him as having fangs à la dracula, to further romanisize his legend.
The site of Raja Bersiong's fort, which is long gone, used to be a rubber estate. At time of writing (September, 2015), I saw that it has been cleared and is about to make way for housing development.
Another view of the site of Raja Bersiong's fort (22 July, 2015)