The strangest thoughts ricochet through your mind when you’re standing inside a dank, dripping passage bored into the side of a Colorado mountain.


One: Boy, am I lucky. I never had to spend day after day in a place like this, chipping away at the walls of a glittering labyrinth of tunnels lit only by flickering candle. Office cubicles really aren’t so bad after all.


Two: What if the ceiling collapses? What about bathrooms? And stale air? Why is it so cold in here? And where did miners eat their lunches?


This year marks the 160th anniversary of the Colorado Gold Rush, which geared up 11 years after the California Gold Rush of 1848.


Prospectors didn’t really find much gold in Colorado early on, but to people living on the East Coast, even a little gold represented one more reason to ditch home and head west for a brighter future. They loaded up the wagons, hollered “Pikes Peak or bust!” and rode out of town with high hopes. And in 1859, some of them did hit gold.


The Country Boy Mine outside of Breckenridge, Colo., is one of dozens of mines around Colorado that offer public tours each summer. I’ve donned a hard hat for a sneak preview of this one from Paul Hintgen, who manages the place.


To get to the end of the 1,000-foot tunnel where I’m now standing, I passed a toy canary perched in a cage just inside the entrance. I listened as Hintgen explained how miners once grabbed a metal tag with their name on it from a board when they went into the shaft. That way, the boss knew if someone was still in the tunnel when the workday ended.


I got interested in Colorado mining a few years ago, after picking up a copy of “Tomboy Bride: A Woman’s Personal Account of Life in Mining Camps of the West” by Harriet Fish Backus. The book, written by a woman whose husband worked the mines above Telluride a century and a half ago, tells her experience of life in Colorado during the Gold Rush.


Country Boy Mine operated from 1887 until 1946, and crews harvested gold, silver, tin and zinc here. Mining was so big in these parts that Breckenridge had electricity before Denver did.


“That’s how important mining was,” Hintgen tells me.


RELATED: 48 hours in Breckenridge, two ways


The most famous gold nugget ever found in this area, a glistening hunk called Tom’s Baby, was pulled from the Gold Flake Mine on nearby Farncomb Hill. It weighed in at more than 13 pounds, and, according to legend, one of the prospectors who found it swaddled it in a blanket and paraded it proudly around town like an infant. The chunk was put on a train to Denver but never made it. Someone discovered it in a bank vault in 1972, about 2 pounds lighter. It’s now on display in the Coors Mineral Hall at the Denver Museum of Nature and Science.


In its later years, Country Boy Mine supplied high-grade zinc and lead used during World War I and II.


Mining operations ended here in 1946, but the facility opened to tours in 1994. Hintgen says there’s still valuable mineral inside the mountain, but it’s unlikely anyone will try to dig it out. That would mean scraping away the top part of the mountain to access the ore, not something a resort town like Breckenridge is likely to do.


Hintgen then tells me this mine is reportedly haunted. No one knows if anyone died in an accident here, because there are no records of that. But when Hintgen invited ghost hunters to investigate, they reported 13 separate ghosts lingering in Country Boy’s tunnels and passages.


I shiver a little. It’s 45 degrees inside the mine year-round.


To drive home the point, Hintgen flips off the lights, and we’re swallowed by inky blackness.


We don’t see any ghosts, though, and head back out, with a quick stop so Hintgen can show me how workers once drilled holes in the rock walls, tucked in sticks of dynamite and hollered, “Fire in the hole!” before setting off blasts to extend passageways.


We file out of the tunnel and back into daylight, where Hintgen points out the quick way down to the parking lot — a 55-foot ore chute suitable for sliding.


The Country Boy Mine isn’t the only remnant of Breckenridge’s mining history.


Old mining routes such as Minnie Mine and Sally Barber now function as hiking and biking trails, and the Blue River, where miners once panned for gold, is now a fly-fishing destination.


Breckenridge itself is home to the Gold Panning Championships, scheduled for June 2020.


All over Colorado, the story is the same. Leadville, once a mining hotspot, today is known for its mountain bike trails and 100-mile marathon bike race. Visitors can take a walking tour that highlights 50 buildings that date to 1870 in that town’s preserved mining district.


Closer to Denver, in Georgetown, an old narrow-gauge railway runs through a mining tunnel called the Ice Palace. Today cyclists and hikers can pass through it.


Silverton, Idaho Springs, Alma, Fairplay, South Park, Crested Butte and Old Colorado City all played a role in the boom days, too.


The history fascinates, and the towns make fun destinations. Plus, a tour of an old mine lets you see one part of Colorado you probably haven’t seen before — the underside.


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