Between 1876 and 2002, the people of Lead, South Dakota, extracted $3.5 billion worth of gold from the Homestake mine. It was the town’s main business, and when falling prices and diminishing returns finally shut it down, no one was sure what to do with the remaining 8,000-foot hole in the ground. Then, in 2007, the National Science Foundation decided that an 8,000-foot hole would be the perfect place to put its proposed Deep Underground Science and Engineering Laboratory, or DUSEL, a massive research complex that will include the world’s deepest underground lab.