It was 2004 when, to lighten the city traffic, was built the Mezzolombardo road tunnel towards the “Non Valley” and the “Sole Valley”. The dolomia, dug during the works, presented numerous cavities: essential spaces to… grow. In these empty spaces, 200,000 years ago, a hydrothermal circulation, between 45°C and 70C°, solidified creating exceptional rarities: perfect calcite crystals, large up to 20 cm.