What do you do when a meteor crashes into Earth and leaves a 25 km wide impact crater? Why, you build a town out of it – some 15 million years later.

Welcome to Nordlingen, Germany. First settled in 838 CE, the town is situated at the center of the meteor’s impact site, and is built from the stone of its remains. And as you might expect from something extraterrestrial, it’s no ordinary stone. Termed “suevite”, it’s a grainy rock with shards of glass, crystal and diamonds. Yes, diamonds — these stones, which have been used to construct the town’s wall, church, and homes, are shiny. The church, St. Georg’s, is said to contain about 5,000 carats of diamonds.

The diamond-fortified stones may be at least partly why these structures are still standing today, with the medieval wall surviving even the 30 Years’ War in the 17th century. Only a few Bavarian towns still have their medieval walls, such as the more popular Rothenberg, but unlike there, Nordlingen’s wall is completely intact and goes all the way around, a full 3 km.

Additionally, walking the stone steps to the top of the church tower (the ‘Danielturm’), which reportedly gives the best viewing angle to see the edge of the crater, gives the occasional brilliant flashes of light as well.

Other towns including Rothenberg have used suevite as a construction material, but none to the extent of Nordlingen. The crater is estimated to contain 72,000 tons of diamonds – however, the diamonds are all microscopic, at less than 2 mm wide. Unable to be mined and sold on their own, they simply add a strong and shiny quality to the stone that surrounds them.

Throughout history, the town’s inhabitants didn’t think much of the glimmering stones, and didn’t even know they were formed by a meteor until the mid-1960s. Prior to that, they believed the crater they lived in was caused by a volcano, until investigation by geologists Eugene Shoemaker and Edward Chao found the true cause.

Since then, not only has the town had to update all the school’s textbooks, it’s also converted a 15th century barn into the Ries Crater museum and welcomed NASA and European Space Agency astronauts. While preparing for the Apollo 14 and Apollo 16 missions, astronauts visited Nordlingen to study the suevite to better prepare them for what they might encounter on the moon, and in return, they brought a moon rock back to display at the museum, where it remains to this day.

They have also been able to provide more insight to the meteor that started it all: it’s estimated to have been 1 km wide, weighed 3 billion tons, and traveled at 25 km/second. Despite being only 1 km wide itself, its impact site is 25 km wide, and 1,500 meters deep. The tremendous heat and force generated at impact turned its carbon bubbles into tiny diamonds.

The meteor strike also led to formation of an ancient salt lake, which then created the nutrient-rich soil that is now home to the pine and conifer forests that surround the crater’s ring. Abandoned suevite mineshafts and quarries can also still be seen littered around the region.

Perhaps due in part to the abundant mining available, Nordlingen had a strong medieval presence. It was located next to a Roman settlement on a prominent road up from Italy (part of what is known today as the Romantic Road), and was known as a “Free City”, bustling with trade. Its local fair was considered one of the most important in the area. The Scharlachrennen, a horse riding tournament, has been held in Nordlingen with earliest records in 1463.

But human civilization in the area goes back even further. In 1908, a cave system was discovered just outside Nordlingen, with strange findings inside: 33 human skulls arranged in concentric circles, facing the sunset and painted in red ochre. They are estimated to be 8,000 to 9,000 years old, but the question remains what they were doing there in the first place – perhaps the ancients also sensed the special charge of the extraterrestrial diamond-infused crater and used it for ritual purposes.

Another fun fact: if you’re thinking you’ve seen this picturesque red-roofed town before, you probably have: Nordlingen was used as a backdrop in the film Willy Wonka and the Chocolate Factory. Now you know exactly where it was they were soaring over in the glass elevator – and you even can visit and see for yourself the rich influences, both worldly and off-planet, that make this town so special.