Columbia State Historic Park is a preserved gold rush town located three miles north of Sonora in the Sierra Nevada foothills. It was declared a National Historic Landmark in 1961. The business district has been preserved with shops, restaurants, and hotels. There is a museum, authentic period fire equipment, volunteers dressed in period costume, a stagecoach you can ride, a gold mine you can visit, and you can also pan for gold. Due to its period authenticity, many movies and TV shows have been shot in Columbia.
According to the California state park website:
It is a real town, it never actually closes. Most businesses are open from 10:00 am to 5:00 pm. Many restaurants, hotels, saloons and other establishments have longer hours. Almost all businesses are closed on Thanksgiving and Christmas Day.
Depending on the timing of your visit and the activities you choose to partake of, you can spend either a few hours or the entire day in Columbia. I visited Columbia several years ago and didn't spend a lot of time there, since it was a weekday in the Autumn, so there weren't a lot of activities going on at the time. There are more activities on the weekend and during the summer, when the costumed docents are available for tours and information. Gold Rush Days are celebrated the second Saturday of every month. Panning for gold is a great activity for kids, as you are actually just panning from a sluice and not actually standing in a stream. I would like to go back to Columbia and spend more time.
Unfortunately, I can't find any pictures from my visit, but if I come across them, I will post them.