I’ve had this page of manhole covers open in the browser for the past few days, one of those things in the should-look-at-more-closely category. I’ve had a better look now, and I was reminded of seeing Japanese manhole covers, and they come in a much greater variety of designs (and colours!), so I was wondering why manhole covers are often so dull. I watched a How it’s Made on manhole covers the other day, and there’s no real reason why a city, region or département (say) shouldn’t have its own design.
This site has a good collection of images of Japanese manhole covers, four of which I’ve cut out below.