Whether salt, limestone, or some other material, mines eventually fall into disuse. But in a number of cases, they’ve had unexpected second lives. From botanical gardens to racetracks to bookstores, here are 15 old mines put to innovative new uses.

1. CONCERT VENUE

When former opera singer and radio producer Margaret Dells Fors and culture editor Åsa Nyman learned of this unused limestone quarry in Dalarna, Sweden, they realized the location and landscape—protected from noise pollution and providing high-quality acoustics—would make a terrific amphitheater. Renaming it “Dalhalla” (a combination of Dalarna and Valhalla), it hosted its first concert in 1993 and continues to draw world-class acts like Led Zeppelin, Patti Smith, and Norah Jones.

2. UNDERGROUND THEME PARK

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Hundreds of feet below ground in Transylvania, an old salt mine (dating back to the 17th century) has been turned into Salina Turda—a bizarre amusement park complete with mini golf, bowling alley, carousel, and even a Ferris wheel. For those more interested in history, the park still contains some of the old mining machinery, and tours are available. 

3. BUTCHART GARDENS 

A limestone quarry in the early 1900s, serving cement needs from San Francisco to Victoria, British Columbia, this Vancouver Island spot has been turned into a large-scale botanical garden. Once the limestone deposits were exhausted, Jennie Butchart (wife of the quarry’s owner, Robert Pim Butchart) took things over, turning the pit into a Sunken Garden. Over the decades her descendants have added to it and expanded it, and it was designated a National Historic Site of Canada in 2004. 

4. THE EDEN PROJECT

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A Cornwall, UK­ crater from which china clay was once extracted, this site was transformed in the 1990s into The Eden Project, an educational botanical garden in a series of biomes. It houses what they claim is the largest rainforest in captivity as well as a number of contemporary gardens and exhibitions, plus a stage for summer concerts and family events.

5. UNDERGROUND SPA

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The 800-year-old Wieliczka Salt Mine, located in Poland, has pioneered a treatment it's dubbed “subterranotherapy,” in which the supposedly pollution-free underground air is believed to help aid the respiratory system, serving as an ideal treatment for those suffering from asthma, allergies, or respiratory infection.

6. HYPOXIC RUNNING TRACK

Speaking of wellness treatments, in Yanahara, Japan, a former iron-ore mine has been converted into an underground racing track. The low levels of oxygen found so far underground actually mimic the conditions of high-altitude racing, making this an attractive facility for athletes preparing for a race much higher, or lower, than they are accustomed to.

7. SUBTERRANEAN RACETRACK

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For those more interested in car racing than foot racing, book a ticket to the Swedish island of Gotland, where an exhausted limestone quarry has been turned into Gotland Ring, a world-class racing track that is now used for motocross, car races, performance driving, and more.

8. FAKE LAKE

When the people of Gilbert, Minnesota opted to fill their open-pit iron ore mines with water, turning them into a manmade lake, they looked to A Prairie Home Companion for inspiration, dubbing it Lake Ore-Be-Gone. Through a land reclamation project started a few years ago, beaches and boat landings were added, turning this into a beloved local spot for families.

9. INDEPENDENT BOOKSTORE

A silver mine for the first quarter of the 20th century, this site in the Cobalt Mining District of Northern Ontario was turned into a grocery store, Firefighter’s Museum, and, in 2014, a bookstore and publisher’s office for White Mountain Publications, which runs its own writers’ contest and poetry competition. 

10. MUSHROOM FARM

The subterranean conditions of an old limestone mine in Worthington, Pennsylvania proved conducive to mushroom farming. Creekside Mushrooms Ltd. converted the mine into a sprawling mushroom farm, capable of producing 60 million pounds of mushrooms each year and employing hundreds of locals in the effort. According to the company, it was the largest mushroom facility in the world and the only underground mushroom operation in the nation. Sadly, it went out of business in 2010.

11. SALT CATHEDRAL 

Some 200 yards underground near the Colombian town of Zipaquirá sits a functioning Roman Catholic church built into an old salt mine. Carved salt sculptures and a 16-foot cross are among the startling sights in this unusual house of worship. 

12. SOCCER STADIUM

The home of Portugal’s Sporting Clube de Braga, which now seats more than 30,000 people, was once a granite quarry. Designed by Pritzker Prize–winning architect Eduardo Souto de Moura, the venue was created in harmony with the mountain and other natural surroundings.

13. MUSEUM 

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Speaking of salt mines, the vast deposits of rock salt below the Polish city of Wieliczka were mined back in the 13th century. Though it fell into disuse in the 20th century, it has now been converted into an elaborate museum about the local mining industry, showcasing vintage tools and machinery. 

14. DATA CENTER 

Burying data 22 stories underground sure can make it feel more secure. Iron Mountain built its national data center in an unused 145-acre limestone mine in Butler County, Pennsylvania. Safe from almost any natural disaster, it also boasts its own café and fire department.

15. GOVERNMENT OFFICE

Another hyper-practical (some might say “boring”) use of an old mine is the U.S. Office of Personnel Management Retirement Operations Center, which has turned a 230-foot deep limestone mine in Boyers, Pennsylvania into a bureaucratic center where 600 employees process millions of documents. The mine’s labyrinthine caverns are filled with tens of thousands of file cabinets.