If you’re not a professional typographic practitioner, you might fall into the trap of thinking that certain upper-case letters (such as H, I, N and O) will look exactly the same upside down (i.e. when rotated 180 degrees about their z* axis). But subtle complications can, and do arise when there are serifs involved. One of the very few websites devoted to photographically documenting public displays of accidentally rotated letters (where letter = N) can be found here. Upside Down N – A Collection of Unruly ‘N’s.
“From an early age on, I’ve noticed signs where the letter N with serif is accidentally placed upside down. In fact, this awareness was the first thing that triggered me to become a graphic artist. Many years later, in 2004, I started to photograph this phenomenon all over the world.
To spot upside down N’s you must travel. Upside down serif N’s are everywhere. And nowhere. Most upside down N’s remain unseen for years because they are hidden between ‘normal’ letters.
We hereby invite you to become an N-hunter and photograph your finds.”
* Note: The resolutely non-standardised world of 3D co-ordinates is the source of much confusion. For clarity, the co-ordinate system we have in mind is this one, where the xy plane is the plane of the screen you are looking at, and the ‘z‘ axis is the ‘depth’ into (or out of) the screen.