Four Incredible Things That Used to Exist in South Dakota

South Dakota is famous for its historic landmarks - like the faces on Mount Rushmore or the spires of the Badlands -  but the state's history is also littered with some incredible sights that have completely vanished from the map.

From record-breaking "spaceports" in the Black Hills to industrial fortresses made of "slime" (you read that right), here are four incredible things that used to exist in South Dakota that you won't believe were ever real.

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The 300-Foot "Monster" Slide at Sherman Park

Decades before Sioux Falls had a bustling downtown or modern water parks, it had the Sherman Park Slide. Built in 1913 by the Sioux Falls Metal Culvert Company, this wasn't your average playground equipment. It was a 300-foot-long industrial marvel that began with a 100-foot vertical drop. The slide was so high that it actually bridged over the park road, allowing horses and buggies to pass underneath while thrill-seekers flew overhead. It eventually curved west toward the river, ending what was essentially a pioneer-era roller coaster.

The Stratobowl: South Dakota's Original Spaceport

Tucked away in the Black Hills near Rapid City is a natural limestone depression known as the Stratobowl. While it’s a quiet hiking spot today, in November 1935, it was the center of the scientific world. The Explorer II, an enormous helium balloon, launched from the floor of the bowl and reached a record-breaking altitude of 72,395 feet. This was the first time humans were able to see the actual curvature of the Earth and prove that we could survive at the edge of space, decades before NASA was even formed.

The Homestake Slime Plant

In the West River town of Lead, a huge industrial fortress once dominated the hillside. Known as the "Slime Plant," this maze of redwood tanks and heavy machinery was built in 1906 to extract every possible grain of gold from the Homestake Mine's crushed ore (which they called "slime"). The structure itself was a masterpiece of early 20th-century engineering. As mining technology modernized, the plant became obsolete and was eventually dismantled, taking a huge piece of the region's industrial skyline with it.

The Walled City of "Dinosaurs"

During the Great Depression, a man named Ole Quammen wanted to give the people of Lemmon a reason to hope (and a place to work). He oversaw the construction of a literal castle made entirely of petrified wood and fossilized prehistoric remains. While the park still exists today, the original "Walled City" featured jagged towers and enormous fortress walls that made it look like a medieval castle on the South Dakota prairie. Over nearly a century, weather and safety updates have smoothed out the original "wild" look of this fossilized city.