Thanks to an article at Gizmodo, I discover the following manhole covers art in Japan. In Switzerland or France we do not have manhole cover that beautiful.
A manhole cover is a removable plate forming the lid over the opening of a manhole, to prevent anyone from falling in and to keep unauthorized persons out.
Flickr Pool -- Japanese Manhole Covers: More than 400 photos there.
Design Manhole Collection: You can click a prefecture and then the town names in the grid on the following page to display the manholes for that area.
Some other url