Several people guessed that the illusion was the fact that it resembled the Eiffel Tower. Unfortunately, that's not it - but I'm pleased to have that comparison. Thanks! I finished it off with a border and some foo-foo in the corners to distract the eye a little bit more. Maybe you can see it better in this shot.
Want to test your friends' ability to catch the "mistake"? Here is the freebie! Simply click on the chart and print the picture from your browser, or click here for a pdf file.
I stitched a mini Eiffel Tower and the year of my trip on the other side. The adorable little Eiffel Tower pattern is from Happy Stitch Project on etsy.com.
Just a small side note: I remember now why I hate to stitch pre-finished items. This was absolutely one of the most frustrating projects I've every done! I am a dedicated "stabber" and I had to stitch on this pouch with the sewing method since it's so small. I think next time I'll sew the pouch myself AFTER I stitch the designs :)