The prambanan temples actualy situated in the so-called "Valley of God", following the immaginary lines that connect between the Indian Ocean and Merapi Volcanoes, that once became sacred places according to the tradition of Javanese peoples. In the valley of God, you could found bunch of the temples such as Sewu, Idjo, Banyunibo, etc. I hope you still have a time to explore them ;) regards!