In this optical illusion we see two buildings and it looks like the building on the right is in danger of falling over and crushing everyone underneath. It's an architectural disaster!

But like the title says, this is an illusion. In fact, both halves of the image are identical. In this Instructable we'll quickly go over a way to make one of these images on your own.

## Step 1: Get a Picture

First you'll need a picture looking up at a building. Flickr is a great place to look. If you're going to be using this image where someone will see it, be nice and use one that has a Creative Commons license.

Look for pictures where the perspective is from below so that there is a distinct difference in the angles of the sides of the building. This gives a strong feeling of where the lines would converge. The second image shows where the vanishing point is.

As such, you want a building with straight sides. Good keywords to search for are "building," "up," and "perspective."

The source image can be found here.

## Step 2: Crop It

The next step is to crop the image so that there less open space to the right of the building.

## Step 3: Double Up

Now just repeat the image and you're good to go!

Inspiration for this illusion from The Leaning tower Illusion by Frederick Kingdom, Ali Yoonessi and Elena Gheorghiu.

## Step 4: An Explanation

Parallel items have the same vanishing point. So the vertical lines of these two buildings would converge on the same point if they were normal. since they are very divergent here, we are tricked into thinking that the building on the right is leaning far off to the side.
Why the one on the right and not the one on the left? maybe because we read the image from left to right and we accept the first as the image with the correct perspective?
Naw, it's due to the fact that the towers are on the right sides of the images. Try copying the image and horizontally flipping it in photoshop. The left one will look like it's falling over instead.
I'm not sure that it's the removal of sky that causes the illusion, it's the fact that the photo is lopsided that does it for me. Because the right hand edge of the building is vertical in the photo it accentuates the appearance of "lean" in the building to the right of it.
I removed a bit of the sky just so that the buildings would be closer. What I think does it is that the vanishing points are so different.
It took three guys to do this?
That is interesting. 2 of the same image and one looks like it is leaning.