Yogyakarta - is said to be a cultural center of Java having even special status. The sultan lives there in his palace and it's also the best place to see and buy batik. There's a huge complex called Kraton, which is a maze o little streets with the sultan's palace in the middle. You can go and see multiple sections of the palace. The water palace is where the sultan used to soak in pools with his many wives - in fact they had their own pool, the sultan would watch them from above and throw a flower in; the one who grabbed the flower had the priviledge to join sultan in his pool :) Then there's the main palace, where the today's sultan still lives and only part of which is available to the public. It also has a collection of presents the sultants received from other world leaders, some of which are very funny-looking. We had quite a hard time trying to figure out what's where and how to get around as the whole complex is enclosed by walls and very confusing.
Prambanan - very famous temple complex, about 10 miles off Yogya. To get there, we just rented a motorbike in town and headed towards Solo - it's right on the highway, impossible to miss. It was damaged in one of the big eqrthquakes couple years ago, so there's still some reconstructions going on. It's a complex of more or less fallen apart stone temples. Their main feature is the fact, that they're put together by.. nothing. It's just finely masoned, puzzle like structure. No wonder it falls apart with each earthquake :) In any case, it's still very impressive and worth seeing, despite the huge crowds.
Borobudur - the other famouse temple, about 40 miles off Yogya. This one is not as easy to get to on bike, so we went there on a combined day-tour (with Dieng plateau). This time it's just one temple, looking like a major pyramid. When it was found, it was just a big pile of stone all falllen apart, but then UNESCO poured in some $$$ and got it all fixed up. It's quite impressive work actually - it consists of multiple levels, all depicting certain stages of human life, something like Dante's inferno. All the levels have carving on the walls, which must have been real fun putting together - something like working on 3d puzzle, each piece weighting 300lbs. There are budha's under bell-shaped structures on the top - touch one and you'll have all the luck you'll ever need :) We were there for the sunset, but weather didn't cooperate :(
Dieng plateau - couple hours drive from Yogya, it's a plateau famous for its temples, volcanic activity and potatoes :) We went there on the combined tour with Borobudur and it turned out to be a pefrect combination. We spent about 3 hrs on the plateau itself, which is quite enough to see all that's worth seeing there. The temples are tiny (comparing to Prambanan anyway) and within walking distance. We also went around the 3 lakes, which are said to have different colors. If it wasn't for all the noisy water-pumps, it would actually be a very nice hour-long stroll.