It was an honour for me to pay a visit to world's first manhole art exhibition. With such beautiful art hanging on the walls, it's hard to tell that these are all manhole covers!

Yes seriously, manhole cover looks better than the water colored frame.
I think you struck a novel idea of a manhole art gallery. Who knows, it could inspire the next trend in art galleries and may be even in auction houses for the real, antique manhole covers. Let's start preserving those wonderful pieces as collectibles.