The Wieliczka Salt Mine has existed — and been recognized as a marvel — for so long that its famous visitors include Copernicus, Goethe and Chopin. This incredibly unique space was officially recognized as a UNESCO heritage site in 1978 but had been used as a salt mine near Krakow, Poland, since the 13th century.

During the Renaissance, it was one of the biggest businesses in Europe, since salt was recognized as a key ingredient for safe food preservation. The mine continued to produce salt until the late 1990s, but now it's one of Poland's main tourist attractions with over a million visitors every year.

Tourist stairs the lead to the subterranean church inside the Wieliczka Salt Mine, Wieliczka The staircase that leads down to the subterranean church inside the Wieliczka Salt Mine in Poland. (Photo: akturer/Shutterstock)

It's pretty obvious why so many flock to see it. This large complex more than 1,000 feet underground is a marvel of centuries of human construction and decoration. The entire mine is over 178 miles long, but only part of that is open to visitors, who can take a two-mile-long tour of the various rooms and artworks.

Detail of the handmade reliefs on the walls at the Wieliczka salt mine. Detail of the handmade reliefs on the walls at the Wieliczka Salt Mine. (Photo: Milan Gonda/Shutterstock)

The oldest art was created by the miners themselves, and in recent years artists and artisans have added to the craftsmanship, sculptures and reliefs throughout the public areas of the mines.

The Erazm Baracza Chamber and subterranean lake in the Wieliczka Salt Mine, near Krakow, in southern Poland The Erazm Baracza Chamber and subterranean lake in the Wieliczka Salt Mine. (Photo: Juli Scalzi/Shutterstock)

In addition to the chapel pictured at the top of this page, there are many other decorated spaces and tunnels. One chamber's walls were carved to resemble wood, as churches were built of at the time, while others feature Disney-like recreations of history in the mines.

In the 19th century, huge chandeliers — made of salt crystal, of course — were brought in to fill the spaces with light. There's even a lake (above) and a grotto (below).

The Jozef Pilsudski Grotto (19th century) Wieliczka Salt Mine near Krakow Poland The Jozef Pilsudski Grotto was created in the 19th century. (Photo: akturer/Shutterstock)

Surprisingly, there's also a health resort within the mine — the air is said to be beneficial to those who have respiratory issues. You can visit for the day or stay overnight to experience what the website calls "subterraneotherapy."

A depiction of how workers mined for salt through the centuries. A depiction of how workers mined for salt through the centuries. (Photo: puchan/Shutterstock)

Staying overnight in the salt caves could be a unique adventure — accommodations are in the Stable Chamber, which used to be where the horses were kept in the 12th century when horses were used to power salt excavations. According to the resort's site: "...there is no pollution in which the environment on the surface abounds today; there are no allergens, bacteria and fungi, or harmful electromagnetic radiation, either." Sounds peaceful, for sure.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.