Ride the elevator cage almost a half-mile underground, then take the electric train another three-quarters of a mile to the deepest part of this old iron mine, which closed in 1962.
At the very bottom is a mighty, football-field sized room that shelters an laboratory where physicists are looking for dark matter (which shouldn't be difficult to find in a mine, har-har) and are trying to measure the mass of neutrinos. Going this deep and this far underground requires a tour of 90 minutes, so bring lots of warm clothes and the ability to forget that between you and the surface lies more than 2,300 feet of solid rock.
