Surakarta, also called Solo or Sala, is a city in Central Java, Indonesia of more than 520,061 people (2009) and density of 11,811.5 people/km. This 44 km city bordering Karanganyar Regency and Boyolali Regency to the north, Karanganyar Regency and Sukoharjo Regency to the east and west, and Sukoharjo Regency to the south. On the eastern side of Solo lies Bengawan Solo River. The city is the seat of Surakarta Sunanate kraton (palace/court). Alongside with Yogyakarta, Surakarta is the heir of Mataram Kingdom that was split into two kingdoms in 1755.