A video accompanies visitors on a fascinating scientific and historical investigation, a “detective story” whose solution, found by two American scientists, Walter and Luis Alvarez, is rooted in the Bottaccione gorge, near Gubbio, in Umbria. Following the trail of a vein that is too rich in iridium to be “terrestrial,” we are projected into the past by 66 million years, when the impact of a huge meteorite caused the extinction of a huge number of species, including many of the great reptiles that had dominated the planet up to that point. This crisis, the world’s fifth great mass extinction, paved the way for the success of the life forms that managed to survive, including us mammals