Concrete and crystal
After getting his degree in geography-topography, Lerner János (1952) was a university professor for twenty years. Besides teaching, he gained a lot of experience in tourism as a tour operator, and he also worked in local nature conservation. He published many educational books about geography. He's been the editor of SpektrumTelevision since 1998. He joined the team of Filmdzsungel in 2008 as a director, editor and screenwriter.
There is a mysterious tunnel system in depths of Tábor Hill in Buda. The Királylaki Cave opens from it, that was discovered in 2011. Due to the abundance of diverse crystals, the cavern is an outstanding natural value. The film images this unknown underground world.