MINNEAPOLIS (WCCO) — If you’re in Alaska, you should visit Denali. If you’re in Arizona, you should visit the Grand Canyon. If you’re in California, you should visit Yosemite National Park.

And, according to USA Today, if you’re in Minnesota, you have to stop by Niagara Cave in Harmony.

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“The cave became the first in the world to use solar power to light its underground cavern in 2015. The underground tours follow passages carved by an ancient underground stream,” the newspaper’s Bruce Guenter wrote. “Check out the 60-foot underground waterfall that gave the cave its name, an echo chamber, fossils and even a subterranean wedding chapel.”

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The cave was actually discovered by three pigs, so the story goes. The animals fell through a sinkhole in a pasture in 1924 and their squeals led searchers into a previously unseen series of underground tunnels.

For many centuries, water had slowly been chiseling, molding and sculpting through a half mile section of limestone beneath a Fillmore County farm field.

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USA Today also put together a list of fun things to do in each state ranging from free to just under $20. Mall of America was Minnesota’s choice in that category.