Humans have spent centuries studying Stonehenge, yet it still has a few tricks up its sleeve. In recent years, for instance, research has shown the size of the world’s most mysterious megalithic monument is much larger than previously assumed, giving enthusiasts a whole new set of questions to ponder.

While many secrets of the sacred site will remain hidden, here are some impressive facts about Stonehenge that have come to light:

1. It's not alone. It has long been thought Stonehenge stood in isolation, but recent research — described in the BBC Two documentary "Operation Stonehenge: What Lies Beneath" — employed techniques to scan below the surface and has uncovered something different. Underground maps show 17 previously unknown shrines and hundreds of other archaeological features around the site, including types of monuments never seen before.

2. It started with deer antlers and bovine bones. Stonehenge dates back to around 5,000 years ago. It began as an earthwork — a bank and ditch called a henge. Archeologists think the ditch was dug from tools made of red deer antlers; the chalk underneath was likely removed with shovels made of cattle shoulder blades.

3. It dates back to the late Neolithic. Merlin the magician, the Romans and the Druids have all been given credit for building Stonehenge, but now archaeologists think the first stones were raised around 2500 BC by the native inhabitants of late Neolithic Britain, according to English Heritage, the government body that looks over England’s historic sites. In a 2019 study, researchers used DNA from Neolithic human remains to determine the ancestors of Stonehenge's creators likely arrived in Britain from Anatolia, or modern-day Turkey, around 4,000 BC. Researchers generally believe Stonehenge was built to track the sun’s movements, namely the summer solstice.

stonehenge inner and outer circles of stones The stones of the inner and outer circles. (Photo: Brian C. Weed/Shutterstock)

4. It includes imported bluestones. The first section, the inner circle, is comprised of about 80 bluestones that weigh a whopping 4 tons each. The stones were quarried in the Prescelly Mountains at a site known as Carn Menyn. Remarkably, the quarry is located more than 150 miles from the site. Modern theories suggest the stones made the trip courtesy of rollers, sledges, rafts and barges.

5. It might have been a healing shrine. Why they would select stone from so far away remains without a definitive answer. One theory suggests the builders believed the rocks of Carn Menyn were endowed with mystical properties for recuperation, and since visiting the mountains was difficult, bringing the stones to Stonehenge was a way to create a more accessible shrine for healing.

6. Some of the stones weighed more than three adult elephants. The giant stones that form the famous outer circle are made of sarsen, a type of sandstone. Most experts believe these stones, weighing an average of 25 tons, were transported about 20 miles from the Marlborough Downs. The largest stone, the Heel Stone, weighs about 30 tons. While much of the route was (relatively) easy, modern work studies estimate no fewer than 600 people would have been required to get each stone past Redhorn Hill, the steepest part of the journey.

7. A piece of Stonehenge went missing for 60 years. After cracks were found in one of the sarsen stones during excavations in 1958, workers drilled cylindrical cores from the stone before inserting metal rods to secure it. The three core samples seemed to vanish afterward, but as CNN reports, one of them just reappeared six decades later. It turns out one of the workers had saved the 108-centimeter-long core, displaying it on a wall in his office. He returned it to English Heritage in May 2019, on the eve of his 90th birthday, and researchers say studying this core could reveal new insights about the origins of the sarsen stones.

8. Raising the stones required ingenuity. To raise the stones, a large hole was dug, with half of the hole lined with wooden stakes. The stone would be moved into position and forced upright using ropes and possibly a wooden structure; the hole was then packed tightly with rubble.

9. The lintels were tricky, too. To secure the upright stones with the horizontal lintels, Stonehenge’s builders made mortise holes and protruding tenons to ensure stability. The lintels were then fit together using tongue-and-groove joints.

summer solstice at Stonehenge Thousands gather at Stonehenge in 2017 to witness the sun rising on the longest day of the year. (Photo: Chris Allan/Shutterstock.com)

10. It can be kind of a circus. While those who have never visited Stonehenge may imagine it as a sacred site secluded in idyllic natural surroundings, in fact, there is a major highway less than 100 yards from the stones. In addition, the site is surrounded by what Brittania.com calls “a commercial circus,” complete with parking lots, gift shops and a cafe.

11. It makes a lot of cameos. Stonehenge has become such a recognizable symbol that it has made cameo appearances in many cultural features. It was in the Beatles film "Help!," for example, as well as Roman Polanski's "Tess" and the classic mockumentary "This is Spinal Tap." It has shown up in books, computer games and television shows. And let's not forget "National Lampoon's European Vacation," in which Clark Griswold bumps into one of the stones and knocks them all down, one by one, like a giant stack of dominoes. The Neolithic builders would not be pleased.

Editor's note: This article has been updated with new information since it was originally published in September 2014.

11 curious truths about Stonehenge
The world's most famous ring of standing stones has been studied for centuries, yet we learn something new about it all the time.