Step into a unique piece of Mongolian history at the former Berkh fluorspar mine, now a fascinating underground museum. You'll descend 45 meters into the earth to walk through the very tunnels where ore was extracted for the Soviet Union. This immersive complex gives you a real feel for the country's industrial past, showcasing historic photos, documents, and actual mining equipment in a place where few travelers have been. It's a surprising and memorable journey into the region's heritage, far from the usual tourist trails.