Valencia under foot

Manhole covers all over the world are cast of iron, and all of them must withstand water, chemicals, abrasives, and [one more].  They have to have designs that are simple and strong. But beyond that, they can vary widely in their size, shape, and layout. Because they reflect local needs and attitudes.  I like to pay attention to them in a new city.  

Here in Valencia the manhole covers have their own special story.    The other round cover shows bands of 

One cover, right, is made in the shape of a guitar--a traditional source of Valencia's fame. 

Another design, below, is round--the best shape for a manhole cover to insure that it can never fall into the hole.  The bands of decoration display the city's signature mosaic motif of irregular tile, which appears everywhere, most notably in the white tiling on on its futuristic opera house dome. 

From Madrid, a beautiful manhole cover.
for an energy supply company.  Its elongated
letters and leafy border suggest  Art Nouveau. 

Note that blank space is usually filled with pattern or letters or ornaments.  Smooth surfaces, or sudden changes of level, would risk being slippery.  The best manhole covers support the foot while they inform the eye and cover the hole.