ShotHotspot has mapped 18 abandoned places in Calaveras, California, ranked by how often they're photographed, viewed and voted for. The most popular are Chinese Camp Abandoned Chinesecamp, Preston Castle and Churchyard Chinese Camp Abandoned. Some are private property or unsafe, so get permission before you visit.
We don't know whether you're allowed to visit any of these places. Many are private property, closed to the public or unsafe: get permission from the owner or the relevant authority, and take safety precautions.