The Strange Mystery of Florida’s Coral Castle

coral castle entrance

[Image courtesy of Bitter Southerner.]

At the center of every great mystery, there is a puzzle. When people look at the pyramids of Egypt or the Moai statues of Easter Island, the puzzle at heart is obvious: how? How were these incredible objects created?

A similar, and no less puzzling mystery, can be found much closer to home for most Americans: the Coral Castle of Florida.


[Image courtesy of The Bohemian Blog.]

Less a castle and more a varied arrangement of stones into walls, shapes, doorways, and more, the Coral Castle is composed not of coral, but of oolite limestone blocks weighing literal tons. More than 1,000 tons of rock are part of the Coral Castle’s elaborate layout, which was assembled and expanded from 1923 to 1951.

Some of those monstrous stones are seamlessly joined into different structures. Others are so perfectly balanced that they can open like a revolving door with the gentlest push.

There is a sundial, a telescope, and even stone rocking chairs carved from single pieces of rock.

coral castle moon

[Image courtesy of Bitter Southerner,]

It’s an engineering marvel, to be sure, but what separates the Coral Castle from some of those other creations we mentioned above is the fact that we know who built the Coral Castle.

One man. Ed Leedskalnin.

coral castle tools

[Image courtesy of LiveScience.]

Using basic tools like picks, winches, ropes, and pulleys, Leedskalnin created the Coral Castle in secret, allowing visitors to ponder just how he was accomplishing this remarkable feat.

It’s particularly remarkable when you consider that Leedskalnin only had a fourth-grade education, having gone to work at a young age.


[Image courtesy of The Bohemian Blog.]

Of course, it’s also worth noting that Leedskalnin was a bit of a kook, claiming he had learned the secrets of the architects of King Solomon’s temples by studying books about the pyramids at the local library.

And yet, he created something amazing. So amazing, in fact, many people attribute the Coral Castle to supernatural efforts, not merely the engineering prowess, cleverness, and determination of a hardworking man.

coral castle stairs

[Image courtesy of LiveScience.]

Over the years, many peculiar theories have circulated surrounding the Coral Castle and Ed Leedskalnin. Unreliable eyewitnesses claimed to see coral blocks floating in the air like balloons while Leedskalnin worked at night.

Some believe Leedskalnin levitated the blocks with telekinesis or psychic powers, or by singing the stones into place. Others attribute the Castle to some sort of strange manipulation of gravity, antigravity, magnetism, ley lines, or earth energies. And, of course, alien technology has been floated as a possibility as well.

(Some people even believe there’s a hidden cipher lurking in several tracts written by Leedskalnin, just waiting to be found to reveal his secrets.)

coral castle chairs

[Image courtesy of Bitter Southerner.]

A friend of Leedskalnin’s wrote a book about the physics and engineering of the Coral Castle, entitled Mr. Can’t Is Dead. It’s one of many books that claims to explain how the Coral Castle came to be.

To me, the Coral Castle seems like one giant mechanical brain teaser, a math problem more about leverage and patience than the paranormal.

And yet, I can’t help but stare at some of these creations with awe. Maybe this one of those puzzles that’s better left unsolved.


[Image courtesy of The Bohemian Blog.]

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PuzzleNation Product Review: Domino Maze


[Note: I received a free copy of this game in exchange for a fair, unbiased review. Due diligence, full disclosure, and all that.]

What is it about dominoes that makes watching them fall such a satisfying experience? Is it the meticulous prep work required for a domino display? The balance and hand-eye coordination required to place each one? The danger of upsetting the whole thing before all the pieces are in place? The potential energy harnessed and ready to be unleashed as soon as the last domino is set up?

Whatever it is, it makes for one heck of a conclusion to a logic puzzle.

The creative minds at ThinkFun have conjured up a delightful twist on their traditional complete-the-path brand of logic puzzles, incorporating not just gravity, but the click-clack cacophony of a chain reaction in a new challenge for younger puzzlers and more experienced ones alike.

In today’s product review, we’re taking a look at Domino Maze.


[One Challenge Card’s preset pieces in place. Note the three gates, each already balanced to topple over when the domino path crosses through.]

Domino Maze builds on the usual domino-stacking skills and tricks — splitting the path, making sharp turns, redirecting kinetic energy — by adding sequential gates that your domino path must pass through in order to complete each challenge.

The gates are numbered one through three, indicating the order in which you must hit your targets. (The gates are carefully balanced, so when a domino hits the target, the weight on top flips over, raising the numbered flap high AND knocking over the next domino in your chain.)

Similar to other ThinkFun games, the puzzle includes Challenge Cards, which increase in difficulty as you work your way through the deck. Beginner and Intermediate Challenges give way later to Advanced and Expert puzzles that will have you wracking your brain to employ the required number of dominoes, build your path, and hit the gates in precise order.

Note: Be aware that you need a completely flat surface for this game. The grooves will hold the domino, but the slightest mistake could send them tumbling. That’s particularly true when the staircases are involved. There’s no need to add a level of frustration beyond the natural challenge of the game by fighting gravity AND the designers’ puzzles.


The Beginner-level cards are your introduction to the puzzle, taking you through the motions of how to place the dominoes, utilizing the numerous grooves in both the base and the elevated platform. As you proceed, the game adds new wrinkles to the game, like using the two pivot pieces (allowing you to change direction in a single move), splitting your path with the diagonal grooves.

That elevated platform is an especially devious and clever addition, since it not only requires more dominoes (to traverse one or both of the staircases that connects the platform to the base), but requires multi-dimensional thinking, like starting your path underneath the platform versus atop the platform. In this manner of solving, Domino Maze echoes other top-down logic puzzles in the ThinkFun library like Gravity Maze and Roller Coaster Challenge.


[Two different angles of the same Challenge Card, mid-solve.]

You also slowly develop a sense of what I call “domino math,” the ability to look at the number of dominoes you have to work with, and immediately limit your choices and potential solutions based on what you know. For instance, three dominoes in a straightaway can cover half the board, but it costs three dominoes to make a 90-degree turn in one square, so you begin to recognize where resources MUST go vs. where they COULD go.

That’s a huge benefit down the line, when your dominoes (through splits and other maneuvers) must maximize their usefulness. It seems daunting when you look at a Challenge Card and see that you have to place 18 dominoes, but honestly, that’s less intimidating than looking at a card with gates scattered all over, and seeing you only have seven or eight dominoes to work with.


But whether you’re a younger puzzler just getting started with logics, an experienced puzzler who likes the idea of combining a little hand-eye coordination with your solving, or a domino enthusiast looking for a new challenge, you’re bound to find the ever-escalating gameplay of Domino Maze to be a treat. (And just imagine the challenging pathways you could construct with two sets. Or a Rube Goldberg device made of ThinkFun puzzles.)

Watching those dominoes fall and those gates flip with the push of a single fingertip is a very fun and satisfying way to confirm that your puzzling skills are up to snuff. Plus there’s the sound, and the tactile sense of accomplishment with a path well-deduced and well-built.


Very few puzzles offer that kind of fanfare for a proper solve, and the logical foundation behind cause-and-effect is rarely as enjoyable as it is in Domino Maze.

Domino Maze is available from ThinkFun and other participating retailers.

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A Shift in Puzzly Perspective


I’ve had 3-D puzzling on the brain for a few days now, after a conversation about video games with a well-informed friend of mine.

What do I mean when I say 3-D puzzling? Well, I don’t just mean a puzzle that exists in three dimensions. I mean a puzzle where the solving experience requires all three dimensions.

Think about your average maze or a jigsaw puzzle. Although they’re three-dimensional objects, the solving is two-dimensional. Yes, there are certainly variations on these themes, like maze cubes where you navigate a marble from one place to another, or 3-D jigsaw puzzles that allow you to reconstruct famous landmarks. But these still rely heavily on two-dimensional solving.

Compare that with the iconic puzzle video game Portal, for instance. Portal requires you to accomplish different tasks, and you can only do so with your portal gun, a device that allows you to connect two different locations on the map.

[Image courtesy of Game Informer.]

That requires a complete realignment of your perspective, because you can walk in a straight line through one portal and emerge above, below, or at a 90-degree angle from where you started. This isn’t two-dimensional thinking anymore.

Between 3-D printing techniques and the constantly evolving engines behind video game systems, we’re seeing more and more examples of three-dimensional thinking in puzzles, and I’m perpetually amazed by what creators and designers come up with.

Check out this video of gameplay from the new puzzle game Etherborn:

Your character navigates elaborate three-dimensional landscapes, and gravity is wholly dependent on how your character is oriented at the moment. So you need to be clever enough to use the landscape in order to move your character in very unorthodox ways.

It’s fascinating, a step beyond some of the puzzles seen in previous games like Portal and Fez. (In those games, gravity still only worked in one direction, whereas Etherborn breaks even that fundamental baseline.)

I think this sort of puzzling appeals to me so much because the change in perspective that comes from solving in an additional dimension completely rewrites the rules we thought we knew.

Imagine for a second that you’re inside a corn maze. Now think about the paper mazes you’ve solved. See the difference? In the first scenario, you’re beholden to the meager information you get from following each path, whereas in the second, you can plan a route from above because you have much more information. You can see dead ends and avoid them.

The three-dimensional scenario is far more challenging than the 2-D solving you’re doing with the paper maze.

ThinkFun managed a similar feat with Gravity Maze, a puzzle game that required you to move a marble from the starting cube to the ending cube. The main challenge was that you had to build the path with only the given materials, and then just drop the marble in. All the puzzling happened at the beginning, and then you became a bystander as the marble traversed the solution you built.

This isn’t just plotting a path like in a normal maze, it was understanding a chain of events you were setting in motion, like cause and effect. It’s like building a simple Rube Goldberg machine and watching it go.

But whether you’re manipulating portals, shifting perspectives, dropping marbles, or solving corn mazes, you’re pushing your puzzly skills into new dimensions. And that’s just the puzzles we have now. Imagine what comes next.

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PuzzleNation Product Review: Strata Sphere

In today’s product review, we look at a puzzle game with a simple premise: get your spheres from the top level of the grid to the bottom before your opponent does. All that stands between you and victory? Four levels of sliding walls and a wily opponent.

Today, we tackle the multi-layered challenge of Strata Sphere.

Strata Sphere is a puzzle game for two players that challenges you to outthink and outmaneuver your opponent in order to get your four spheres through the grid first. Imagine the gravity-fueled fun of Ker-Plunk with the chain-reaction planning of chess, and you’ve got something approximating Strata Sphere.

This game is all about tactics and adaptation. First, you and your opponent take turns placing the twelve sliders into the grid. There are four levels to the grid, each level accommodating three sliders.

As you can see, some of the sliders have holes in different places, and others have no holes at all. Placement of these sliders is only part one of the game, but it’s a crucial one.

Once all twelve sliders are in place, the players choose their color spheres (red or black), and take turns placing them into the columns atop the grid, one sphere per column.

[As you can see, some of the spheres have already dropped to level 2,
thanks to the placement of holes in several of the sliders in level 1.]

Now the real strategy begins, because with each turn, a player may select any slider and pull it out of the grid one notch. (Each slider has three notches, allowing it to interact with three different columns.) As the game progresses, players can also push sliders in one notch.

Whether the slider moves out of the way of a sphere or moves a hole into place so a sphere may drop through, each move has the potential to drop a sphere a level (or two!) closer to freedom.

After one or two games, we actually ended up putting the game on a lazy susan, so we could rotate it, observe the grid more easily, and gain better access to all the sliders.

This form of three-dimensional puzzle-solving is a real challenge, because you’re not just dealing with your opponent’s next move, you’re dealing with all the setup (slider placement, sphere placement) that preceded it. Here’s where your ability to adapt comes into play, because all that strategy can go completely out the window at a moment’s notice.

Tension ratchets up quickly as you and your opponent maneuver back and forth, manipulating the sliders and helping gravity guide your spheres through the grid and toward the open tray below. The first player to free all four of their spheres wins.

Strata Sphere is a puzzle game that’s easily explained to younger players, but one that offers a great deal of complexity for older players as well, taxing your tactical abilities, spatial awareness, and your ability to seize unexpected opportunities when they arise.

Being forced to take turns makes long-term planning more difficult, and the four levels of gameplay will push your visualization skills to the max. (Planning out moves on a chess board is one thing, the multi-tiered slider system of Strata Sphere is quite another.)

The gameplay is engaging, the design is simple and elegant, and I daresay there’s no more satisfying sound than the click of a well-earned sphere hitting the tray, freed. What a treat.

Strata Sphere is for ages 8 and up, available now from Family Games America.

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PuzzleNation Product Review: Gravity Maze

This week, we’ve got mazes on the brain, so it’s only appropriate that the folks at ThinkFun sent us a maze-based puzzle game to try out. Join me as we give the full PuzzleNation Blog treatment to Gravity Maze.

In a previous review, I accepted the challenge of ThinkFun’s Laser Maze, a logic game requiring players to direct, divert, and split an actual laser beam with mirrors in order to light up various targets on the board. You had to map out the beam’s path in your head and figure out how to place the game pieces in order to hit every target.

Impressively, Gravity Maze has raised the stakes, building on Laser Maze’s premise and adding a third dimension. Whereas Laser Maze only operated along length and width to cross the board, Gravity Maze’s falling marble has to be shuttled across the board while descending from its launch point as well.

With color-coded tower pieces of various heights and configurations — some levels have ramps to the next lowest level, others have open spaces, and still others house turns for the marble to navigate — it’s up to the solver to add only the pieces listed on the card in order to build the marble’s path to the red target box, each tower clicking into place.

There are 60 challenge cards that range in difficulty from beginner to expert. In the earliest challenges, there are only a few pieces on the board, and there’s a clever black dot system telling you which direction each set tower faces. But as you get accustomed to using the towers and move from beginner to intermediate cards, a new wrinkle is added: sometimes, a tower must be placed horizontally in order to complete the path.

And as you progress into advanced and expert cards, you have to get craftier. The marble often has to double-back, passing through the same tower multiple times on its way down.

Check out the path the marble takes to reach the red target box in this one:

[It’s hard to draw a line in three dimensions.]

You can see the colored ramps that direct the marble from the blue tower to the yellow to the green, and then back across. The marble then drops out of the blue tower and into the purple one beside it, where it makes a right turn, passes through the yellow tower, drops into the gray tower, and lands in the red target box.

This next-level spatial awareness offers a serious challenge to puzzlers of all ages, and I admit, some of these advanced and experts had me stymied for a bit.

Heck, sometimes, a tower must be used horizontally, but above the game board itself.

Gravity Maze is easily the most challenging ThinkFun product I’ve had the chance to tinker with, but that didn’t make it any less fun. The box says “Ages 8 to adult,” and I agree wholeheartedly. Puzzlers of any age will enjoy tackling these three-dimensional logic problems and seeing the marble wend its way into the target box.

[To check out other PuzzleNation reviews of ThinkFun products, click here.]

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