The Nevada County Narrow Gauge Railroad ran from Colfax to Nevada City and Grass Valley from 1876 until 1942, and this small museum at the old Nevada City depot keeps the memory of it alive. The collection includes vintage locomotives, rolling stock, and a good archive of photographs and artefacts from the line's operating years.
The narrow-gauge railway was the economic lifeline of the area's mines and mills, hauling ore down to the standard-gauge line at Colfax and returning with supplies and passengers. The museum is staffed largely by volunteers — some of them, as one docent famously noted, holding credentials as rocket scientists. Call ahead or check the website before visiting, as opening hours vary by season. It's a smaller site but genuinely engaging if you're interested in Gold Country history.