Riddle: What invention lets you look right through a wall?




Our Riddle App is starting to gain a little traction now. It is called “Riddle Robot Eyezak, the Puzzle Master”. You can find our Riddle App on the Play Store (android) and the App Store (iOS). In our Riddle App, Eyezak asks you over 5000 riddles, and each riddle can be a “dad-joke,” “easy,”, “intermediate,” “advanced,” or “genius” level. This particular riddle is classified as an “intermediate” level riddle. We will discuss some possible answers and why window is the correct one.

What inventions can you think of that might let you see through a wall? Let me list a few things I can think of right now, and we will see how each of them fares at answering the riddle.

  • x-ray machine
  • camera on other side
  • a friend with a walkie-talkie
  • a hole
  • a window

X-Ray Machine

Have you ever broken a bone or been to a chiropractor? Both of these would have probably exposed you to an X-Ray machine. X-Ray machines are designed to see through, well, anything really. In modern day however, they are most commonly used in the medical field to see inside the body. X-Ray machines can see through most materials, but some materials either cannot be seen through at all or they leave varying density translucent parts on the final picture.

X-Ray machines are quite proficient at seeing through Humans and helping doctors track down internal body issues, but are they good at seeing through walls? Technically they can see through some walls, but definitely not all walls. For instance, if the wall were made of some sort of metal or reenforced concrete, an X-Ray machine would be completely useless. Beyond that though, their primary function is not to see through walls. Our Riddle App question is looking for something more specific.

Camera on Other Side

Eyezak would appreciate this answer, but does it actually resolve when you consider every part of the question? Well, cameras have several purposes. One of its primary functions however, is allowing you to see action in a place that is not in direct line of sight, like the other side of a wall. You could easily have a webcam setup on the other side of a wall, and have it streaming to a device on your side of the wall.

The question is, would Eyezak the Riddle Robot consider this the answer to our riddle? The answer is probably not. The reason is because, even though you are seeing what is on the other side of the wall, you are technically not seeing “through” the wall. To see “through” the wall, you would need to look directly at the wall, and be able to see right through the wall, as if it were not there, to the other side.

This answer is circumventing the question. You are not actually seeing “through” the wall. You are seeing the image of something on the other side of the wall through a recorded facsimile of the action on the other side. Because you are cheating with this answer, it is not the correct one. Eyezak the Riddle Robot from our Riddle App would be proud of you trying to beat him, but unimpressed by your incorrect answer. What possible answer is next?

Friend with Walkie-Talkie

Did you ever play cops and robbers? Some times, if you have a lot of people with the game, and you all decide to allow props, you can get a bit creative with how you play. If planned effectively, your entire team can be in constant contact using walkie-talkies, which could give you the edge to evade or execute capture! Your buddy might see a member of the opposing team coming your way, and give you an update over the air, giving you time to adjust your position or strategy.

The same thing applies to this riddle posed in our Riddle App by Eyezak the Riddle Robot. You could have a friend on the other side of the wall with a walkie-talkie, waiting and dictating to you every detail about what he can observe on the other side. Depending on the friend, this might even be better detail than you can observe on your own, and might even be better than seeing it yourself.

But does it answer this riddle? Probably not. The question asked by the Riddle App is asking how you can “see through” a wall. While yes, if your friend is super descriptive, you might have an extreme amount of detail, and may even be able to visualize the other side of the wall in your head. Still though, you are not “seeing through” the wall. You are only visualizing what is over there. This is certainly not the answer Eyezak or the Riddle App want. Let us move on.


A hole?! Would our Riddle App or our Riddle Robot want you to put a hole in your wall?! If you had a hole in your wall, you might have some big problems. First, a hole in a wall is completely defeating the primary purposes of the wall. Walls should protect you from the elements. They should prevent, at least to some degree, unauthorized access. They should be sturdy enough to withstand a reasonably sized attack. With a hole in them, none of these things are satisfied.

Despite that, technically it does allow you to see through the wall itself. You can look towards the wall, and see clear through it because, well, there is no wall there anymore. But there is a problem with this answer. It is unlikely that anyone, including Eyezak or the Riddle App, would consider this an invention. Inventions tend to be less destructive, and more helpful. Also, holes are not really invented, they are discovered, which is something else entirely.

Because of this, a “hole” is probably not the answer anyone is really looking for here. Maybe a more specific type of hole, that does not break the basic function for a wall, might actually be the answer though. How about a window?


A hole that is expertly carved out and filled with a transparent material like glass, is called a “window,” at least in most parts of the world. The Riddle App is asking if we have an invention that allows us to see through a wall. As discussed above, while answering the riddle, we need to maintain the integrity and primary function of the wall itself, all while implementing this invention to help us see through it. Does a “window” work here?

Yes. Windows, like holes, allow you to see straight through a wall. When you look at the wall that has a window on it, you can see the stuff on the other side of the wall, unencumbered. Windows also have the added benefits of protecting you from the elements. You are also protected, to some degree, from unauthorized access. In addition your window, if designed properly could even withstand a moderate amount of attack.

It sounds like the window meets all the criteria posed by Riddle Robot Eyezak and the Riddle App. You can see through the wall, the wall’s function is in tact, and you are not cheating the rules of the riddle. Hopefully, this is the clear answer. If you still have questions though, feel free to ask in the comments.


Eyezak from our Riddle App asked what invention can let you see through a wall. The answer is a window, and that is what this image is a picture of.

Even though our Riddle App does not really require you to know any background about windows, you might find it neat to learn something new about them. This invention has been around for quite some time now, and Eyezak, the Riddle Robot, from our Riddle App is counting on you knowing that.


Windows have been around a long time, like the 13th century BC! Apparently around that time, the invention did actually start as just, well, just holes in the wall. Soon they upgraded to being covered with some animal hides and such with mechanisms to hole back those covers. Then shutters came. Then, after that, we finally started seeing glass-like material used in window creation.

Around that time, even paper was a thing used to cover windows, but there were some even more inventive ways of creating a light delivering source through a wall, used by various cultures. For instance, some people used translucent animal horns, or thin pieces of marble, or even brown glass jars that were flattened into pane like shapes. It was not until almost 1000 years later that we saw the first actual glass, transparent windows we know today.


This invention has many, many different types, each serving a variety or purposes, and originating in various parts of the world. You might see a Cross Window that forms a Latin Cross. There is also Eyebrow Windows, which have a defined shape on the top. Fixed Windows do not open and are usually extremely decorative. You might find these types in churches over other buildings.

You also have Single, Double, or Horizontal Sash Windows, where the top or bottom or both parts of the window can move, creating a full opening. Fold Up Windows are interesting, and look similar to sash windows but instead the pieces fold together, inward, and pin at the top of the window frame. There are so many types of windows, it would be hard to list them all here with a description. You can find a pretty complete list in the “Windows” link above.

Hopefully this quick preview has triggered you to want to learn about this invention on your own. Our Riddle App does not require you to know this stuff, and Riddle Robot Eyezak does not either. It is our hope that our Riddle App will encourage you to find stuff out on your own and explore the vast amount of knowledge there is out there to be had!

One Last Thing:

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