It’s notable that the Bosnian Pyramid organization in recent years have been concentrating almost exclusively on opening up the tunnels beneath the hills and with good reason, they are genuinely mysterious.
The tunnel complexes are vast and intricate and strangely at some point all the side entrances were sealed off by dry stone walling and fill material, there is the suggestion of some dating evidence that this was happening around 4,600 years ago according to the project leader Semir Osmanagić.
Because of everything that has surrounded this project it is going to be ignored by mainstream archaeology
http://www.megalithicodyssey.com/symposium