Sangiran is a very important archaeological excavation site (so important it gained World Heritage status in 1996), where some of the best examples of fossilised skulls of prehistoric ‘Java Man’ (Pithecanthropus erectus) were unearthed by a Dutch professor in 1936.
The town’s main (if not only) attraction is its small museum, with a few skulls (one of Homo erectus), various pig and hippopotamus teeth, and fossil exhibits, including huge mammoth bones and tusks. Guides will also offer to take you to the area where shells and other fossils have been found in the crumbling slopes of the hill.
Take a Purwodadi-bound bus from Solo’s bus terminal and ask to be dropped off at the Sangiran turn-off (4000Rp), 15km from Solo. It’s then 4km to the museum (around 10,000Rp by ojek).