I recently heard that Nashua, NH is the only place in the world with triangular-shaped manhole covers. I'm sure that upon reading this, many of you have already begun feeling quite envious that your hometown cannot make this claim. Sorry. Not everybody's hometown can be so special.

I had a little bit of time on my hands this afternoon, so I decided to find out if this odd claim to fame was even true. And in my internet searches, I discovered that there are numerous other people who had some extra time on their hands...

The University of Idaho posed an internet math challenge related to this topic: Have you ever wondered why manhole covers are round instead of square? The answer is found in this very property: a square manhole cover could be picked up, rotated, and dropped through the hole it covers. However, a circular manhole cover won't fit through that hole no matter how it is rotated. Maybe sometime someone will manufacture manhole covers shaped like the Reuleaux triangle!

The math guy who wrote this would be psyched if he ever came to Nashua and discovered that such manhole covers already exist!

One article on manhole covers exposed the myth that manhole covers are circles because it is the only shape that would keep the lid from falling into the hole. "A 'curved triangle' has a constant width--just like a circle. It would certainly work as a manhole cover. In fact, you can make a manhole cover out of any shape with an odd number of sides. Beginning with a five-sided shape called a pentagon, for example, you can construct a rounded pentagonal shape that has a constant width. Imagine walking down the street and finding differently shaped manhole covers on every block!"

Whoa. Manhole covers of different shapes on every block? That's just a little too wild and crazy for me to imagine!

I even found a website that is dedicated to photographs of manhole covers.

And from what I could find, it does appear that Nashua is unique in the world for its triangular covers.

Do you know of anything random or interesting about your city? I'd love to hear about it.