Cutting 2,341 feet into the earth, Soudan Underground Mine is the deepest mine in Minnesota, and one of the only mines in the world that also plays host to a physics laboratory.

Opened in 1882 when rich ore deposits were discovered, Soudan Mine was active for the next 80 years until it was donated to the state and deemed a historic site. Sitting basically unused, researchers from the University of Minnesota began work on an underground physics laboratory in the 1980s. Their main objective was to study proton decay, but as science evolved, so did the mine.

Currently, research in the mine uses a MINOS detector and is on the hunt for dark matter, the ever-elusive material that cannot be seen because it does not emit light. The space that holds the neutrino detector fits into a cavern the size of a football field, and is just part of the miles of underground world that comprise the mine.

Today, visitors can take a tour of the mine and physics facility during the summer months, and spend roughly 1.5 hours on the 27th level, 2,341 feet below the surface.