The largest salt mining site in the world, functioning until the 1990s, placed on the original UNESCO roster of World Heritage Sites. The Wieliczka salt mine features a route for visitors 137 metres below the ground level, through 20 chambers, the floor area of the largest of which, the Chapel of St Kinga, is 927 sq m - as much as the lump of salt extracted from that very place. Its floors and walls, as well as chandeliers has been sculptured from the material that, in the Middle Ages, was more precious than gold.