As we consider river/ sea, as our mother and mountain as our father and we r the children of it! so, we love to be directly with nature! we put our both purpose to be with our nature parents and our caretaker(Bhagwan) by building tempples on their lap! we feel more secure and peace with them , being apart from the crowded place and when we feel peace in mind, there is Bhagwan, there is temple to worship our Bhagwan!