Although I appreciate the population density of Paris, and I understand that small shops are a requirement - this is just too crazy.
While in Paris we stopped at an english bookstore that you literally could not move around in very easily - OK, not at all. It was like 10 pack rats who all share a disturbing attraction to books set up shop in a size of an American master bathroom. I went downstairs in the basement (even worse), and someone else came downstairs. They had to walk backwards and go back up the stairs part way in order to me to get by him. Awesome.