And while the number of any arrondissement can tell you only so much, it is fair to point out that the 1st arrondissement is indeed Number One in many ways: the most ancient, the one most densely packed with sights – the Louvre, Les Halles, Notre Dame Cathedral – and the most bustling. Few people live there (the population numbers for all four central Parisian arrondissements peaked before 1860), but if you are a tourist, there is a good chance that you will spend more time here than in any other arrondissement.
For a walk, I recommend the Ile St Louis, a genteel residential neighbourhood almost untouched by any urban regeneration craze from the last 2 centuries and full of the understated elegance that only old money can buy. The Discreet Charm of the Bourgeoisie indeed.