A highway sinkhole that opened up in Colorado has revealed a long-abandoned railroad tunnel, according to The Lookout. The highway, which runs near the top of a mountain pass, has been shut down while engineers figure out what do about the situation. Authorities are reporting that the tunnel, which is part of the Royal Gorge Railroad route, was constructed sometime in 1880. In short, it’s pretty amazing. Assuming you like staring at holes in the ground, of course.

During my younger days, I fancied myself as a kind of low-rent urban explorer. At one point in time, I managed to find my way into an abandoned commune in Eastern Kentucky that had been completely washed out by a cloud burst in the early 1900’s, an event which claimed the lives of several individuals who called the area home. Discovering that a railroad is running beneath your hometown has to be a thrilling for those who love this stuff sort of stuff, despite the fact the opening has caused a bit of a problem for the Colorado Department of Transportation.

Speak of the DOT, here’s what they had to say about the sinkhole:

After thorough examinations of the sinkhole yesterday involving a variety of engineers, maintenance supervisors, and geological experts, it was determined that the sinkhole is actually a century-old railroad tunnel that collapsed decades ago. The depth of the hole is currently estimated to be about 100 feet, and since the depths reach so far into the earth, much of the soil was still frozen until very recently. When the soil thawed, the hole was exposed.

By the way — if you’re heading up to Camp Hale to check out where soldiers once trained for winter and mountain warfare during World War II, you’re going to have to make a bit of a detour. And when I say a bit, I mean a 60-mile detour. Make sure you plan your upcoming trip according, as it’s currently unclear when the highway will be reopened.