Cave of the Mounds

Cave of the Mounds is the best show cave in the Upper Midwest and an easy half-day from Madison or Milwaukee: a compact, colorful limestone cave in the rolling Driftless country at Blue Mounds, Wisconsin, designated a National Natural Landmark and run with the care that status implies. Its discovery is a classic accident — quarry workers blasting rock in 1939 opened a hole into a chamber nobody knew existed — and because it was sealed until then, the formations are unusually intact: stalactites, stalagmites, columns, draperies, soda straws and flowstone, tinted in ochres, reds and blues by minerals in the rock. Tours run daily year-round, departing at least hourly and often every few minutes in busy periods; the traditional guided tour lasts forty-five minutes to an hour on a paved, lit route, and summer and select weekends bring longer museum-style visits where you move at your own pace with guides stationed inside. The cave holds near fifty degrees in every season. Above ground the property adds gem sluicing and geode cracking for kids, and three free interpretive trails — Karst View, Oak Valley Loop and the Brigham Prairie Walk — that explain the sinkholes and springs of the landscape above. Most visitors spend about two hours. Admission is moderate; book online for summer weekends. Fit: Wisconsin family weekends, a Madison rainy day, and Driftless-region road trips toward the Mississippi.

The cave is small by national standards, and that is its strength: everything is close, well lit and easy to see, so the guide can stop at a single drapery and show its banding or point out a soda straw growing a hair's width per decade. The formation names lean playful — the guides have fun with them — and the colors are the surprise, because Midwestern limestone caves are often monochrome while this one runs warm and varied. The 1939 discovery story is told well, along with the efforts that followed to protect it, including its recognition as a National Natural Landmark.

The setting is the Driftless Area, the corner of Wisconsin the glaciers missed, full of ridges, coulees and spring-fed streams. Blue Mounds State Park sits next door with lookout towers over the Driftless hills, Madison is about half an hour east (the Edgewater on Lake Mendota makes the elegant base), and New Glarus, Mount Horeb and the Military Ridge bike trail fill the rest of a weekend. Fit: families, couples on a Wisconsin getaway, and any traveler between Chicago and the Twin Cities with a few hours to spare.