Another must go, Borobudur Temple is one of the Forgotten Wonders of the World. It is also the largest Buddhist monument in the world. I will not divulge too much information. You gotta see it to be able to fully experience and appreciate the sheer beauty of this structure. For a brief read on the history and technical details of it, go to: http://en.wikipedia.org/wiki/Borobudur. For an even more brief read, go to: http://wikitravel.org/en/Borobudur.