http://www.dailymail.co.uk/sciencet...ent-structure-Indonesia-20-000-years-old.html Dr Hilman said: ‘People think the prehistoric age was primitive, but this monument proves that wrong.’ Some rocks were originally stuck together with a form of ancient glue and have been carbon dated to be around 7,000 BC. The site is thought to have been built for worship or astronomy The terraces are bordered by retaining walls of stone (pictured) that can be accessed by 400 steps rising around 311 ft (95 metres). They date to at least 5,000 BC