It’s easy to assume that, with so many generations of knowledge under our belts, we understand pretty much everything there is to know about the past. Yet the truth is that the answers to many historical mysteries remain tantalizingly unsolved.

Still, just because we haven’t figured out some of life’s greatest puzzles (yet) doesn’t mean they’re not worthy of our fascination. Sometimes, it’s trying to solve them that’s the fun part!

With that in mind, here are 10 mysteries from throughout history that experts still haven’t managed to figure out that just might blow your mind…

1. The purpose of this clay vase from Roman-controlled Britain, found shattered into 180 different pieces, remains unknown. It wouldn’t make sense to store food in something with that many holes, and the opening at the bottom would render it useless as a lamp. Archaeologists who worked for the Museum of Ontario Archaeology even consulted experts in Roman pottery, but no one could identify it. Can you?

Even the question of how the jar got to the museum in the first place is a mystery. It’s been suggested that, in the 1950s, it was excavated from a crater in London in a region that was ruled by Rome around the third century. It was found in a storage room with artifacts from Ur, an ancient Iraqi city with a 5,000-year history, but nobody can say what it was used for.

2. While researching prehistoric climate change in 2011, a University of Colorado team happened upon something strange at a 1,000-year-old Eskimo settlement in Cape Espenberg, Alaska. It looked like a small belt buckle, but it was hundreds of years older than the house where it was discovered. The weirdest part, though, is that it was made in a mold, making it the only ancient artifact ever found in Alaska that was made of cast bronze.

According to radiocarbon dating, the item dates back to 600 B.C.E., but that doesn’t necessarily mean that’s its age. Bronze was actually never used in Alaska at that time, so where could it have come from? It’s most probable that it was an heirloom passed down from generation to generation after being manufactured in East Asia, and it only came to Alaska through trading. Still, experts have yet to figure out its purpose.

3. In 1991, archaeologists in Northamptonshire, England discovered the site of a strange (and apparently cruel) burial that had taken place during the third or fourth century. Of the 35 bodies that were found, only one of them—a man who was in his mid-thirties when he died—was positioned face-down. This itself was not particularly unusual, as it may have been a sign that he had an unfavorable community status. What was really odd was that he also had his tongue removed. His tongue was replaced by a flat rock.

There are no archaeological records of such a practice, and the Romans didn’t even have any known laws about amputating tongues. However, there are other Roman-Britain graves that have been found with body parts that had been replaced by other objects. According to experts, the tongue replacement in question was either a cruel punishment or a considerate way to “complete” his missing body part in the afterlife.

4. In 1948, a British diplomat happened to notice a long wall cutting through the countryside as he flew across Jordan. They were determined to be ruins, since named Khatt Shebib, and they run about 93 miles in a north-northeast and south-southwest direction. They also contain the remnants of roughly 100 different towers. Some sections veer off into different directions, while others are faced parallel to each other.

What makes the wall so mysterious is that, at about three feet high, it was far too short to effectively keep anything in or out. Perhaps it was used for farming purposes? Nobody knows for sure.

5. Ten coins were once discovered during an excavation of Katsuren castle in Okinawa, Japan. At first, the construction workers didn’t think they were anything special; after all, they seemed to be worth just one cent each, and they were fairly modern-looking. At least, that’s what they thought. After they were thoroughly scrubbed, the coins were dated somewhere between 300 and 400 B.C.E. Japanese experts were so shocked that they originally believed them to be part of a hoax!

They dismissed that idea, though, and they later discovered Roman letters and figures on the coins. However, it’s not easy to connect the Romans to the Japanese. There was no known connection between the Roman empire and Katsuren castle, either, so how could Roman coins have ever shown up in Okinawa?

6. In 2001, in the town of Karakiz, Turkey, a local tipped off a group of scientists to an ancient quarry in the region, where they found a life-sized granite lion. There was once another cat attached to the lion, but according to other locals, it was blown up with dynamite because there were treasures inside (as were other similar granite lions). Only the one remained. It dated back to the Hittite Empire 3,200 years ago, back when the now-extinct Asiatic lion was still roaming Turkey. But why was this statue created in the first place?

There’s a theory that the lions were supposed to be a monument to a nearby spring, since the Hittites worshipped whatever sources of water they could find. Still, that’s only one idea. No one really knows yet what the statues’ purpose was.

7. Around 2010, two people with metal detectors in Denmark were lucky enough to stumble upon four large golden rings. The pair then started to explore the rest of the field, situated in the island town of Boeslunde, and found even more gold! It dated back to sometime between 700 and 900 B.C.E., and it was much more than just four rings. There were 2,000 hair-thin spirals, each about an inch long.

The spirals were uncovered between wooden and fur fragments which probably once made up a luxurious box. It’s not known what they were used for, but some have suggested that they were either clothing accessories or perhaps sacrificial objects.

8. In Jerusalem’s oldest bedrock, three V-shaped furrows—each 20 inches long and two inches thick—were found carved into one of the limestone floors. Pieces of pottery indicate that they date back to 800 B.C.E., but nobody knows their meaning or purpose.

9. What’s known as the Indus Valley Civilization first appeared about 4,500 years ago, and it was apparently directly responsible for the ruins made of baked brick in Pakistan’s Harappa and Mohenjo Daro. It was a lively city for a thousand years, with ahead-of-its-time urban planning and a great relationship with nearby Mesopotamia.

Most homes had a bath and proper drainage, there was a complex water-control system, and the streets made up a grid. So why is it that such a clearly advanced culture died out? No one knows.

10. “The Golan Structure” in Israel’s Golan Heights is considered by many to be the most mysterious structure of the Middle East ever since the series of five circles was first noticed from the air in 1967. The outermost ring is a massive 500 feet wide, and excavations on the ground revealed that it was about 5,000 years old. The labyrinthine structure is made up of a combined 40,000 tons of basalt rocks in small stacks.

Most fascinatingly, however, is the huge burial chamber in the center. Researchers believe that there might have been an astrological point to the structure on top of the grave site since the annual solstices correspond with the gaps in each wall.

We may never know the truth about these structures and artifacts, but they certainly are fascinating to think about. Can you imagine how amazing it would be if even one of these mysteries was solved in our lifetime?

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