In the town of Westford, Massachusetts, as far back as the mid-19th century, locals discovered a stone carving on a rock face that appeared to show a figure of a person. They debated whether it was carved long ago by Native Americans or more recently by local kids.

It remained a local curiosity until the late 1930s, when a researcher looking for evidence of Viking expeditions to America paid a visit to Westford and declared the figure was a European-style sword.

Later, researchers stripped off a layer of moss covering much of the rock face to reveal a much larger engraving: a life-sized medieval knight with pleated armor and a shield … or, at least, that’s what many people thought.

The engraving came to be known as the Westford Knight, and the theories around it grew wilder and more controversial, including that it memorialized a Scottish voyage to America in the 14th century and even had connections to the quest for the Holy Grail.

Of course, when talking about Massachusetts legends, myths and folklore, there’s no better person to turn to than Jeff Belanger, folklore expert and host of the New England Legends podcast. He joined GBH’s All Things Considered host Arun Rath for a closer look at the Westford Knight. What follows is a lightly edited transcript.

Arun Rath: Jeff, you recently paid a visit to the Westford Knight. We’ll work our way backward, but first, tell us what it looks like right now when you go there. What do you see?

Jeff Belanger: Well, it’s a surprise — it was a surprise to me — because the first time I went there was back in, maybe, 2006. But today, you can’t miss it.

When you’re driving down the road, there’s a stone monument [that] looks almost like a headstone. There’s a big plaque telling you all of the story. There’s a plexiglass covering that looks almost like an upside-down casket bolted into the rock that covers the original carving.

And then, right next to it, is a full-size, three-dimensional statue of a knight lying down on his back, holding a sword and a shield over his chest, laying there. It is impossible to miss when you’re driving down Depot Street.

Rath: Wow. Looking at the actual rock, does it look like a knight? What does it look like?

Belanger: It requires a lot of imagination. You can kind of scrunch down and look through the plexiglass and look down at the engraving on the rock. It’s a bunch of lines. I’ll grant you, it looks like [it was] probably done by human hands, but it is not obvious.

The best you can see is on the nearby plaque. You can see someone made a rubbing of it a few decades ago, and the rubbing shows what looks like a very crude, very broad-shouldered knight holding a sword upside down.

This looks like something literally I could draw, and I can’t draw anything. So, I mean, this takes some imagination.

Rath: I want to put in a plug for a book that I read that laid out so much of this. It’s by an actual, bona fide historian, David Goodsward, and it’s called “The Westford Knight and Henry Sinclair: Evidence of a 14th-century Scottish Voyage to North America.”

Now, he certainly doesn’t prove that in the book, but the book runs through all the wild theories. Starting off, it does seem that there is something carved into the rock, something very old. And then the question, as you’re saying, comes back to what it is.

Belanger: Right. It was first discovered in 1873 in the town of Westford. They thought it might have been done by Native Americans, which was typically not their style. We don’t find a lot of rocks carved — not saying never, but it’s not typical of Native Americans to carve up rocks.

Then, as time went on, this mystery demanded more attention.

The thing about a mystery is that we both love and hate mysteries. We love them because it’s so fun to wonder and ponder what did this, and why, and who could have been there. But we hate it because we don’t like unanswered questions, and we think if we just work hard enough, we’ll find a definitive answer. Today, when you look at this monument and the statue and everything else, it sure seems like there’s a definitive answer, but I’m not so sure.

Rath: The knight was ultimately sketched out and chalked out, and there are different versions of it from different researchers who chalked out different things, but ultimately — skipping past a lot — there was a design on the shield that got connected with a Scottish knight or Scottish earl back in the 14th century who would have somehow made it to America.

Belanger: Right. So that’s the voyage of Henry Sinclair. In the fall of 1398, Sinclair and his Knights Templar sailed west. He’d heard stories from a lost sailor who’d shown up decades later that he’d found this very temperate, beautiful place, and it was well past Greenland. So, Sinclair sailed west, past Greenland, and then found land, but it was not what was described.

We believe he was probably up in Newfoundland, in Canada. So he toughed out the winter and then, in the spring, sailed south and allegedly found this much more temperate, beautiful place that we would assume is America. Now, is that Westford, Massachusetts? Is that Maine? We don’t know. It didn’t leave exact coordinates back there for us, but we do have a few artifacts that turned up.

It’s fair to say that the Westford Knight got a huge shot in the arm in 1923 when a strange stone was discovered just up the road from this carving. It’s a rock that they now call the Ship Stone because it’s got a very crude drawing of a ship — again, like something I could draw, and I can only draw stick figures — with an arrow. And by an arrow, I mean like an arrow you would shoot, like a bow and arrow. And then, a three-digit number, which is pretty hard to make out. The speculation was maybe Sinclair’s expedition came by here and carved this arrow to sort of point their way back to their ship while they were exploring this new land.

Rath: I actually first learned about the Westford Knight while on a trip outside of Edinburgh, Scotland, because there is a 14th-century chapel there in Roslin that supposedly is connected with Henry Sinclair. There are carvings inside that church that resemble corn, and that’s cited as evidence because there was no knowledge of corn in the New World, supposedly, in Scotland, back in the 14th century.

I should also point out that most mainstream archeologists and historians don’t take this terribly seriously.

Belanger: No, they don’t, but that’s OK. It’s now a landmark, and what I love about places like this, right — it’s a thing. I hate to use such a non-descriptive word, but it’s a thing. It was just a carving in a rock, and someone said, “Hey, we should protect this thing.”

So, years ago, they put up just a couple of split-rail fence posts because, think about it — Depot Street is a pretty well-traveled road through Westford, and that rock has been through at least a century and a half of New England winters.

And then, since the road has been put in, I mean, think about the plow trucks throwing ice and salt up on the side of the road. There’s no way around it. I mean, when they plow, it’s going to go everywhere, and this is just a few feet from Depot Street.

It’s right off the side of the road on the other side of the sidewalk, so it’s been through a lot. It’s been through a lot of weather, but it’s a thing people looked at it and said, “No, this is something important.”

It started showing up in books, and then, after “The Da Vinci Code” came out, everybody was looking for mysteries. Everybody was literally looking for the Holy Grail. And then you connect A to B, to C, to R, to G, to whatever, and then, you wonder: could the Holy Grail be in Westford, Massachusetts?

Rath: And that’s how we got to the stage where we are now with that really being a thing there.

Belanger: Right. And now it’s a huge thing. But the thing that makes me sad is that when I was first there — 2006 or 2007, something like that — you could look at the rock, you could walk on it if you wanted to, though they asked you not to. You could look at it, and you could ask your own questions. You could really wonder and use your own imagination and try to guess. Is this just ancient graffiti? Is it something more? Is it some message from some people long ago? Does it mark a site where maybe Sir James Gunn possibly died? Gunn would not have been buried below it — it’s a giant slab of rock, there’s no way they moved it — but was he buried nearby? I don’t know. But it allows you to ask those questions.

Now, it’s forced, right? It’s like if I showed you a picture of the clouds, and I said, “See, it’s very clearly a bird flying.” You’d say that’s all you see because I just put that impression on you.

Now, when you see the statue, and you see all the medieval knight stuff, you can’t help but draw that conclusion, even though we’re not certain.