The Berkeley Pit, now a heavily acidic wastewater lake — and tourist attraction — in Butte, Montana, a thriving late 1800s and early 1900s gold, silver, and copper mining boomtown — so prosperous that it was known as "The Richest Hill on Earth." The open-pit copper mine was created by the Anaconda Co. in 1955 to reach rich copper veins below. Many vestiges of those days remain in pockets throughout what is now a city of about 35,000 population. Photo by Carol Highsmith, 2022.