Those Champa Towers/Temples were built b/n 7th and 12 centuries and honour the Mother Godess Po Nagar.
Of the original 7 or 8 towers only 4 remains. The northern tower, Thap Chinh, 23m, was built in AD 817. Two of the towers house a 'linga' - (phallic symbol of male cration and Shiva).