A manhole cover in Japan depicting Mt Fuji. PICTURE:  Kenshi Kingami/Unsplash

Manhole covers are not usually something you'd particularly pay any attention to - but that's not the case in Japan where ornately decorated covers have become highly sought after works of art. The concept apparently dates back to the late 1970s/early 1980s when it was adopted as a way of promoting the importance - and even existence - of the sewage system which at the time was needing to undergo a massive - and expensive - modernisation. The idea caught on, spurred by the country's local municipalities which came up with an ever-widening range of unique designs celebrating eveyrthing from local history, natural beauty spots and attractions through to local luminaries, traditions and festivals. The trend has helped fuel tourism - manhole enthusiasts are known as 'manholers' - with local authorities in some cases using QR codes on manhole covers to provide tourist or emergency information. The popularity of the covers has created a market for collectors with municipalities selling off obsolete covers for the equivalent of $US20 or $US30 (although with covers weighing something like 90 kilograms, it makes for a hefty collection) while cover designs have also reportedly been used to decorate all sorts of tourist tat - everything from tote bags to T-shirts and collectable cards. There's even a Japan Ground Manhole Association and an annual manhole summit which has been held since 2012. Recent additions to Japan's decorated manholes have included a series of Pokemon-themed manholes to mark Yokohama becoming the first town in Japan to host the Pokemon World Championships (indeed, such are the popularity of Pokemon-themed covers that there's a website solely devoted to them).

Below - a manhole cover in the city of  Izunokuni. PICTURE:  Kenshi Kingami/Unsplash.