Fundamentals of Buenos Aires
This tiny little -iron, metal and bronze- plates are mostly ignored by porteños -as the inhabitants of Buenos Aires are called-.
But these plates have been -since the beginning of the city development on the 19th century- an the essential tool to determine the height of the sidewalks, the pavement, the pipelines, and eventually, the whole city.
I had found that just some civil engineers knows about them.
Following the Becher´s concept of repetition I have look for them -they are hard to find, as they are distributed around this huge city- normally close to the corners where two streets meet.