It's a little bit surprising to hear such news today, in the modern world where there is very little left to be discovered. I mean if we take a loot at that picture, there are a lot of settlements around the pyramid, and nobody discovered it before. First, I should mention that this news is not actually a news, because the pyramid was discovered in October 2005. So 3 years already passed.
It became a pyramid only abstractly, just because a news media began its campaign promoting the idea it's the largest man-made pyramid ever. After scientific researches were made, it was proven it's not a pyramid; moreover, researchers had disputes with the Bosnian authorities who supported the mass media's idea. I agree, the hill (Visocica) has a pyramid shape, but it doesn't mean at all it was artificially built.
The idea of pyramid was brought in by a Bosnian metalworker Semir Osmagantic. After conducting certain jobs inside that hill, he found, according to him some "paved entrance plateau and tunnels along with stone blocks" and many other things.
WHAT EXPERTS SAY?
Curtis Runnels, a historical expert, explains that by the following:"Between 27,000 and 12,000 years ago, the Balkans were locked in the last Glacial maximum, a period of very cold and dry climate with glaciers in some of the mountain ranges. The only occupants were Upper Paleolithic hunters and gatherers who left behind open-air camp sites and traces of occupation in caves. These remains consist of simple stone tools, hearths, and remains of animals and plants that were consumed for food. These people did not have the tools or skills to engage in the construction of monumental architecture." The affirmation sounds quite convincing, but, the point is that we can't know for sure who lived about 27,000-12,000 years ago, let alone to specify how and if they were able to dig those tunnels.
Still, detailed expertises were not made, simply because some environment and culture protectors did not allow it, saying that the excavations would destroy a national treasure.