Oro City, CO is a former mining town in California Gulch, named after the Spanish word for gold. It was the site of one of the largest placer gold strikes in Colorado’s history, worth almost $3 million. Gold was discovered in the area in 1859, and a year later, a significant amount of placer gold was found a few miles east of the Arkansas River, leading to a population boom of 10,000 residents. However, as the placer gold was depleted, the population dwindled to a few hundred. Then, in the mid-1870s, silver was discovered, which sparked a renewed rush to the area. Today, several original structures remain, but most are in ruins.