El Raval is about a square kilometre of the tightest housing in Barcelona, with roughly fifty thousand people in it, which makes it one of the most densely populated quarters in Europe. Cut straight through the middle of it is the Rambla del Raval, a wide palm-lined avenue opened in 1999 where five blocks of housing used to stand. Most of the residents were rehoused a few streets away. Botero's enormous bronze cat sits at one end of it.
This was where the city put whatever it did not want inside the walls: hospitals, convents, then in the nineteenth century the factories and the people who worked in them. For a century it was also the most political ground in Barcelona, and in July 1909 its streets carried barricades and burning convents. A quarter of a century on, the avenue works: the Sunday market sets up on it and children play there. It has also drawn a hotel, a film archive and rising rents, and the argument over who the surgery was for has never really stopped.